Storage member, storage amount calculation method, and light source device

Abstract

To provide a storage member, a storage amount calculation method, and a light source device which can accurately calculate an amount of a plasma raw material stored in a container.SOLUTION: A storage member that is a storage member of a high temperature plasma raw material in a light source device for converting the high temperature plasma raw material into plasma using irradiation with an energy beam, and generating radiation includes: a storage part; a temperature adjustment mechanism; and a calculation part. The storage part stores the high temperature plasma raw material. The temperature adjustment mechanism holds the high temperature plasma raw material stored in the storage part in a molten state. The calculation part calculates the amount of the high temperature plasma raw material stored in the storage part, on the basis of power supplied to the temperature adjustment mechanism.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a storage member, a storage capacity calculation method, and a light source device equipped with a storage device. [Background technology]

[0002] Extreme ultraviolet light (hereinafter referred to as "EUV (Extreme Ultra Violet) light"), a type of X-ray, has recently been used as exposure light. The base material of a mask for EUV lithography is made by patterning a material that absorbs the radiation used for EUV lithography on a multilayer film (e.g., molybdenum and silicon) that reflects EUV light.

[0003] The size of unacceptable defects on EUV masks has become significantly smaller, making them difficult to detect, so EUV masks are inspected using actinic inspection, which uses radiation with a wavelength that matches the working wavelength of lithography.

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

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

[0006] LDP light source devices are an improved version of DPP light source devices, and for example, they supply liquid high-temperature plasma raw material (e.g., Sn (tin) or Li (lithium)) containing EUV-emitting species to the surface of an electrode (discharge electrode) that generates a discharge, irradiate the raw material with a laser beam to vaporize it, and then generate high-temperature plasma through discharge.

[0007] LPP light source devices generate high-temperature plasma by exciting EUV radiating species with a laser beam, etc. A known light source device of this type generates plasma by focusing laser light onto droplets of high-temperature plasma raw material ejected in the form of minute liquid droplets, thereby exciting the target material.

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

[0009] This method corresponds to the so-called LPP method, but instead of supplying liquid plasma raw material as droplets, it uses the centrifugal force of a rotor to supply the liquid plasma raw material to the area irradiated by the energy beam. Therefore, compared to methods such as focusing a laser beam on droplets, it is possible to obtain high-intensity radiation with a relatively simple configuration. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-216286 Summary of the Invention [Problem to be solved by the invention]

[0011] In a light source device such as that disclosed in Patent Document 1, there is a demand for a technique for accurately calculating the amount of plasma raw material contained in a container.

[0012] In view of the above circumstances, an object of the present invention is to provide a container member, a method for calculating the amount of plasma raw material contained in a container, and a light source device that enable the amount of plasma raw material contained in the container to be calculated with high accuracy. [Means for solving the problem]

[0013] In order to achieve the above object, a storage member according to one embodiment of the present technology is a storage member for high-temperature plasma raw material in a light source device that generates radiation by converting high-temperature plasma raw material into plasma using irradiation with an energy beam, and is equipped with a storage section, a temperature adjustment mechanism, and a calculation section. The container contains the high-temperature plasma raw material. The temperature adjustment mechanism maintains the high-temperature plasma raw material contained in the container in a molten state. The calculation unit calculates the amount of the high-temperature plasma raw material contained in the container based on the power supplied to the temperature adjustment mechanism.

[0014] In this container, the high temperature plasma raw material is maintained in a molten state by the temperature adjustment mechanism, and the amount of high temperature plasma raw material contained in the container is calculated based on the power supplied to the temperature adjustment mechanism, which makes it possible to accurately calculate the amount of high temperature plasma raw material contained in the container.

[0015] The calculation unit may calculate the amount of high-temperature plasma raw material based on the power supplied to the temperature adjustment mechanism and a predetermined correspondence relationship between power and the amount of high-temperature plasma raw material.

[0016] The housing member according to claim 2, The calculation unit may calculate the amount of the high temperature plasma raw material based on the correspondence relationship of the following formula:

number

[0017] The temperature adjustment mechanism may include a heating mechanism that heats the high-temperature plasma raw material contained in the storage unit, and a temperature sensor. In this case, the heating mechanism may maintain the high-temperature plasma raw material in a molten state by heating the high-temperature plasma raw material based on the temperature detected by the temperature sensor. The heating mechanism and the temperature sensor may be located below the lower limit of the range of fluctuation in the height of the surface of the high-temperature plasma raw material contained in the storage unit.

[0018] The container may have a bottom, in which case at least one of the heating mechanism and the temperature sensor may be disposed at the bottom of the container.

[0019] The container may be connected to a first pipe for introducing the high temperature plasma raw material from the outside, and a second pipe for discharging the high temperature plasma raw material to the outside.

[0020] The housing may have a side portion, in which case at least the side portion of the housing may have a thermal conductivity of 10 W / (m×k) or more and 200 W / (m×k) or less at 300 K.

[0021] The housing may have a side portion. In this case, the side portion may have a dual structure including an outer member, an inner member, and an internal space defined between the outer member and the inner member.

[0022] The high temperature plasma raw material may be tin, lithium, gadolinium, gallium, bismuth, indium, or an alloy containing at least one of these materials.

[0023] A storage amount calculation method according to one aspect of the present technology is a storage member for high-temperature plasma raw materials in a light source device that generates radiation by converting high-temperature plasma raw materials into plasma using irradiation with an energy beam, the storage member comprising a storage section that stores the high-temperature plasma raw materials and a temperature adjustment mechanism that maintains the high-temperature plasma raw materials stored in the storage section in a molten state, and includes calculating the amount of the high-temperature plasma raw materials stored in the storage section based on power supplied to the temperature adjustment mechanism.

[0024] A light source device according to one aspect of the present technology is a light source device that generates radiation by converting a high-temperature plasma raw material into plasma using irradiation with an energy beam, and includes the housing member. [Effects of the Invention]

[0025] According to the present invention, it is possible to accurately calculate the amount of high-temperature plasma raw material contained in the container. Note that the effects described here are not necessarily limited to those described herein, and any of the effects described in this disclosure may be used. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of a light source device according to an embodiment of the present invention. [Figure 2] 2 is a schematic diagram showing an example of the configuration of a plasma generating mechanism, a raw material supply device, and a storage unit. FIG. [Figure 3] FIG. 1 is a diagram illustrating the principle of the present technology. [Figure 4] FIG. 10 is a schematic diagram showing an experimental container member. [Figure 5] 1 is a graph showing the relationship between power and capacity. [Figure 6] 10A and 10B are schematic diagrams illustrating an example of the configuration of a double-structured housing member. [Figure 7] FIG. 2 is a schematic diagram showing a configuration example of a plasma generation mechanism. [Figure 8] 10A and 10B are schematic diagrams showing variations in the arrangement of a heater and a temperature sensor. [Figure 9]FIG. 2 is a schematic diagram showing a configuration example of a raw material supply device. [Figure 10] FIG. 1 is a schematic diagram showing an example of the configuration of a plasma generation mechanism that can recycle plasma raw materials. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present technology will be described with reference to the drawings.

[0028] [Basic configuration of light source device] 1 is a schematic diagram showing an example of the configuration of a 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, the light source device 100 is a device that irradiates a plasma raw material 101 with an energy beam EB to excite the plasma raw material 101 and generate plasma P, and extracts radiation R emitted from the plasma P to use as a light source. The radiation R is EUV (Extreme Ultraviolet) light, X-rays, or other electromagnetic waves.

[0029] 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) in a liquid phase, or an alloy containing at least one of these materials. The plasma raw material 101 corresponds to one embodiment of a high-temperature plasma raw material.

[0030] FIG. 1 is a diagram showing a schematic cross section of the light source device 100 taken along the horizontal direction at a predetermined height from the installation surface, as viewed from vertically above. In FIG. 1, cross sections of portions that are not necessary for explaining the cross-sectional configuration, etc., are omitted to facilitate understanding of the configuration and operation of the light source device 100. Hereinafter, the X direction may be referred to as the left-right direction of the horizontal direction (the positive side of the X axis is the right side, and the negative side is the left side), the Y direction as the front-rear direction of the horizontal direction (the positive side of the Y axis is the front side, and the negative side is the rear side), and the Z direction as the vertical direction (the positive side of the Z axis is the upper side, and the negative side is the lower side). Of course, the application of the present technology is not limited to the orientation in which the light source device 100 is used.

[0031] As shown in FIG. 1, the light source device 100 includes a housing 102, a vacuum chamber 103, an energy beam entrance chamber 104, a radiation exit chamber 105, a plasma generation mechanism 106, a control unit 107, and a beam source .

[0032] 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 so as 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 so as to pass through the entrance hole 102b.

[0033] 1, a beam source 108 that emits an energy beam EB is installed outside the housing 102. The beam source 108 is installed so that the energy beam EB enters the inside of the housing 102 along an incident axis IA. An electron beam or a laser beam can be used as the energy beam EB.

[0034] The light source device 100 is provided with a chamber section C including a plurality of chambers. Specifically, the chamber section C includes a vacuum chamber 103, an energy beam incident chamber (hereinafter simply referred to as an incident chamber) 104, and a radiation exit chamber (hereinafter simply referred to as an exit chamber) 105. The vacuum chamber 103 and the incident chamber 104 are connected to each other, and the vacuum chamber 103 and the exit chamber 105 are also connected to each other.

[0035] The entrance chamber 104 is configured to be located on an entrance axis IA of the energy beam EB, and the exit chamber 105 is configured to be located on an exit axis EA of the radiation R. A collector (condensing mirror) 112 that guides the radiation R is disposed within the exit chamber 105. Furthermore, a plasma generation mechanism 106 that generates plasma P is disposed within the vacuum chamber 103.

[0036] A utilization device such as a mask inspection device is connected to the end of the extraction chamber 105 opposite the plasma generation mechanism 106. In the example shown in FIG. 1, an application chamber 110 is connected as a chamber that forms part of the utilization device. The pressure inside the application chamber 110 may be atmospheric pressure. Furthermore, the inside of the application chamber 110 may be purged by introducing a gas (e.g., an inert gas) through a gas injection path as needed, and may be evacuated by an exhaust means (not shown). A filter film 111 and an opening are provided between the application chamber 110 and the extraction chamber 105 to physically separate the region where the plasma P is generated from the application chamber 110.

[0037] An entrance window 114 is provided in the chamber body 109. The entrance window 114 is arranged at a position aligned with the entrance hole 102b on the entrance axis IA of the energy beam EB. An exhaust pump 117 is also connected to the chamber body 109.

[0038] 1, the emission chamber 105 and the incidence chamber 104 are provided with gas injection paths 116a and 116b, respectively, and gas is supplied from a gas supply device (not shown) to the inside of the emission chamber 105 and the incidence chamber 104. A gas having a high transmittance to the radiation R, such as argon or helium, is supplied to the emission chamber 105. A gas having a high transmittance to the energy beam EB, such as argon or helium, is supplied to the incidence chamber 104.

[0039] The plasma generation mechanism 106 is a mechanism for generating plasma P in the vacuum chamber 103 and emitting radiation R (X-rays or EUV light). As shown in FIG. 1, the plasma generation mechanism 106 includes a rotating body 20, onto which an energy beam EB is incident. The rotating body 20 is disposed in the vacuum chamber 103 so that an irradiation position I of the energy beam EB is located at the intersection of an entrance axis IA and an exit axis EA. The plasma generation mechanism 106 will be described in detail later.

[0040] 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 Fig. 1, the control unit 107 is illustrated schematically as a functional block, but the position where the control unit 107 is configured may be designed arbitrarily.

[0041] 1, in this embodiment, a radiological diagnostic unit 119 is connected to the chamber body 109. The radiological diagnostic unit 119 is disposed at a position where the radiation R emitted in a direction different from the emission axis EA of the radiation R is incident, and measures the state of the radiation R emitted from the plasma P.

[0042] [Plasma generation mechanism, etc.] 2 is a schematic diagram showing an example configuration of the plasma generation mechanism 106, the raw material supply device 30, and the storage unit 40. FIG. 2 shows the plasma generation mechanism 106 of FIG. 1 as viewed from the direction of arrow A (positive side of the Y direction). The raw material supply device 30 and the storage unit 40 are connected to the plasma generation mechanism 106. Note that the raw material supply device 30 and the storage unit 40 are not shown in FIG.

[0043] The raw material supply device 30 comprises a container that contains the plasma raw material 101. The container is connected via a pipe to the raw material container 21 of the plasma generation mechanism 106. In this way, the plasma raw material 101 is supplied to the raw material container 21.

[0044] Because the rotor 20 is immersed in the plasma raw material 101 in the raw material container 21, the rotation of the rotor 20 lifts up the plasma raw material 101 while it is adhering to the rotor 20. The energy beam EB is then irradiated onto the adhering plasma raw material 101 by the beam source 108. The energy beam EB is shown schematically by an arrow in Figure 2.

[0045] At irradiation position I, some of the plasma raw material 101 may scatter without being converted into plasma, or may leak from raw material container 21. This plasma raw material 101 falls to the bottom of raw material container 21 and accumulates in reservoir 40, which is connected to the bottom of plasma generation mechanism 106.

[0046] [Principle of this technology] Figure 3 is a diagram illustrating the principle of this technology. In this technology, it is assumed that the amount of plasma raw material 101 that can be accommodated is calculated in a mechanism such as the container member 50 shown in Figure 3. Figure 3 is a cross-sectional view of the container member 50 cut along the XZ plane, viewed from the positive side in the Y direction. Note that it is assumed here that the plasma raw material 101 is in a liquid state, and the heat of melting that results will not be explained in the principle section.

[0047] The accommodation member 50 has a pedestal 51, an accommodation container 52, a heater 53, and a temperature sensor 54. The pedestal 51 is a stand on which the accommodation container 52 and other components are placed. The surface of the pedestal 51 on which the accommodation container 52 is placed is referred to as the ground surface 59. The accommodation container 52 is a container that contains the plasma raw material 101. The accommodation container 52 has an overall cylindrical shape with an internal space S, and has a disk-shaped top 56 and bottom 58, and a cylindrical side 57. Figure 3 shows a schematic diagram of the plasma raw material 101 contained in the internal space S of the accommodation container 52.

[0048] Heater 53 is arranged around container 52. In this example, heater 53 is assumed to heat plasma raw material 101 so as to maintain the temperature of the plasma raw material 101 at a constant value. Temperature sensor 54 is assumed to be arranged at bottom 58 of container 52.

[0049] [Capacity calculation] In this technique, the amount of plasma raw material 101 contained in the container 52 is calculated based on the power supplied to the heater 53. The plasma raw material 101 loses energy through radiation. In Figure 3, radiation of the plasma raw material 101 is schematically shown by the dark dashed arrows.

[0050] Furthermore, because plasma raw material 101 is in contact with container 52, heat conduction occurs from plasma raw material 101 to container 52. In Figure 3, the heat flow of this heat conduction is indicated by the thick black arrows. As shown on the right of Figure 3, when the amount of plasma raw material 101 increases, the contact area between plasma raw material 101 and side 57 also increases, and so the amount of heat transferred per unit time also increases. Note that although plasma raw material 101 is in contact with internal space S at the top, the pressure in internal space S is extremely low, so heat conduction to internal space S is negligibly small.

[0051] Similarly, radiation and heat conduction to the base 51 occur in the container 52. In Fig. 3, radiation in the container 52 is schematically shown by thin dashed arrows, and heat flow to the base 51 is shown by thick white arrows.

[0052] Here, if the power required by heater 53 to maintain the temperature of plasma raw material 101 constant is W, then according to the law of conservation of energy, the following equation holds when W>0. W = (1) Radiation from plasma raw material 101 +(2) Heat conduction from the plasma raw material 101 to the container 52 +(3) Radiation from Containment Vessel 52 +(4) Heat conduction from the container 52 to the ground surface 59

[0053] "(1) Radiation from plasma raw material 101" is "α1S1T1 4 Here, α1 is the emissivity of the plasma raw material 101 (including the Boltzmann constant), S1 is the surface area of the plasma raw material 101, and T1 is the temperature of the plasma raw material 101.

[0054] "(2) Heat conduction from plasma raw material 101 to container 52" is expressed as "λ1A1(T1-T2)", where λ1 is the heat conductivity from plasma raw material 101 to container 52, A1 is the area of plasma raw material 101 in contact with container 52, and T2 is the temperature of temperature sensor 54.

[0055] "(3) Radiation from the containment vessel 52" is "α2S2T2 4 Here, α2 is the emissivity of the storage container 52, and S2 is the surface area of the storage container 52.

[0056] "(4) Heat conduction from the container 52 to the ground surface 59" is expressed as "λ2A(T2-T3)", where λ2 is the thermal conductivity from the container 52 to the base 51, A is the area of the base 51 in contact with the container 52 (ground surface area), and T3 is the temperature of the base 51.

[0057] From the above, W={α1S1T1 4 +λ1A1(T1-T2)}+{α2S2T2 4 +λ2A(T2-T3)}···(5) holds true.

[0058] Furthermore, consider the case where the liquid level of plasma raw material 101 has increased by Δx compared to the left side of Figure 3, as shown on the right side of Figure 3. If the surface area of plasma raw material 101 in this state is S1' and the area of plasma raw material 101 in contact with container 52 is A1', then the power W' required by heater 53 to maintain a constant temperature of plasma raw material 101 is W'={α1S1'T1 4 +λ1A1'(T1-T2)}+{α2S2T2 4 +λ2A(T2-T3)}···(6) This becomes:

[0059] Therefore, if the power difference between these is ΔW, calculate the difference between equations (5) and (6), ΔW=W'-W≒α1(S1'-S1)T1 4 +λ1(A1'-A1)(T1-T2) (7) and the term relating to the container 52 can be approximated to be approximately the same value and therefore cancels out.

[0060] Here, if the height of the liquid surface of the plasma raw material 101 in the state on the left side of FIG. 3 is L and the radius of the top 56 and bottom 58 of the container 52 is R, then: S1'-S1={R 2 π+2Rπ(L+Δx)+R 2 π}-{R 2 π+2RπL+R 2 π}=2RπΔx (8) A1'-A1={2Rπ(L+Δx)+R 2 π}-{2RπL+R 2 π}=2RπΔx (9) This becomes:

[0061] Substituting these equations (8) and (9) into equation (7), we get ΔW=α1·2RπΔxT1 4 +λ1·2RπΔx(T1-T2) ={2α1T1 4 +2λ1(T1-T2)}RπΔx···(10) get.

[0062] where: k'={2α1T1 4 +2λ1(T1-T2)}Rπ···(11) Then, k' is a constant that depends on the shape of the device, etc., but does not depend on the value of Δx. ΔW=k'Δx (12) This becomes:

[0063] If the amount (volume) of plasma raw material 101 that has increased in the state shown on the right of Figure 3 is ΔV, then: ΔV=πR 2 Δx (13) Therefore, substituting equation (12) into this equation, we get ΔV=πR 2 ΔW / k' (14) Since it is a constant, we add k=πR 2 / k'···(15) It can be said that ΔV=kΔW···(16). That is, ΔV is proportional to ΔW. Therefore, we obtain the following equation.

[0064]

number

[0065] Power W required to maintain the temperature at which the plasma raw material 101 melts x It is believed that the amount V of plasma raw material 101 in the vessel can be determined by calculating and using equation (1). Note that even if the storage vessel 52 is a prism, for example, it is possible to derive a linear equation using the same concept.

[0066] In order to verify the above idea, the inventors created an experimental storage member 62. Figure 4 is a schematic diagram showing the experimental storage member 62. The storage member 62 has a storage vessel 63, a heater 64, a temperature sensor 65, and an information processing device 66. In this technology, the raw material container 21 shown in Figure 2, the vessel for storing the plasma raw material 101 of the raw material supply device 30, and the storage unit 40 are each configured generally like the storage member 62 shown in Figure 4.

[0067] The storage container 63 is a container having an opening at the top. The storage unit 40 in FIG. 2 also has such a configuration. The heater 64 is, for example, a resistance heating type electric heater. Any other heating mechanism may be used. In this example, the heater 64 is disposed on one surface of the bottom of the storage container 63. Of course, other configurations may be used within the scope of the present technology, such as a configuration in which the heater 64 is disposed on only a part of the bottom.

[0068] In reservoir 40 of Figure 2, if the temperature of plasma raw material 101 in storage vessel 63 is low, the used plasma raw material 101 that drips from the light source and raw material container 21 and collects in reservoir 40 will solidify and grow like a stalactite, which may interfere with the operation of light source device 100. For this reason, plasma raw material 101 must always be in a liquid phase. However, the temperature of plasma raw material 101 drops due to radiation and heat conduction to storage vessel 63. For this reason, it is necessary to heat plasma raw material 101 with heater 64.

[0069] The temperature sensor 65 is, for example, a thermocouple, a platinum resistance thermometer (PT100), or the like, but the specific type and shape are not limited. The temperature sensor 65 is disposed at the bottom of the storage container 63. In this example, the temperature sensor 65 is disposed at the lowest side, but this case also falls under the category of the temperature sensor 65 being disposed at the bottom. Of course, the temperature sensor 65 may also be disposed so as to face the bottom.

[0070] Any computer, such as a PC (Personal Computer), may be used as the information processing device 66. The information processing device 66 includes a storage unit and a controller 60. The controller 60 executes various processes related to the present technology. As the controller 60, a device such as an FPGA (Field Programmable Gate Array) may be used.

[0071] In this embodiment, the controller 60 executes a program according to the present technology, thereby realizing a control unit 107 and a calculation unit 61 as functional blocks. These functional blocks then execute the storage capacity calculation method according to this embodiment.

[0072] The control unit 107 controls the operation of the beam source 108 and exhaust pump 117, as well as the operation of the heater 64. In this embodiment, the control unit 107 controls the operation of the heater 64 based on the temperature detected by the temperature sensor 65, and heats the plasma raw material 101, thereby maintaining the plasma raw material 101 in a molten state. In other words, the control unit 107 controls the output of the heater 64 so that the temperature of the plasma raw material 101 is maintained at a constant value.

[0073] The calculation unit 61 calculates the amount of plasma raw material 101 contained in the storage container 63 based on the power supplied to the heater 64. Specifically, the value of the power supplied to the heater 64 is first obtained by the calculation unit 61. The calculation unit 61 then calculates the amount of plasma raw material 101 contained in the storage container 63 based on the correspondence relationship given by equation 1.

[0074] The information processing device 66 may also have a communication unit (not shown). The communication unit is a communication module for communicating with other devices via a network such as a LAN (Local Area Network). This enables communication between the information processing device 66 and the heater 64 or temperature sensor 65, enabling acquisition and control of the detected temperature.

[0075] Besides, the specific configuration of the housing member 62 is not limited. The container 63 corresponds to one embodiment of the container portion. The heater 64 corresponds to one embodiment of the heating mechanism. The heater 64 and the temperature sensor 65 correspond to an embodiment of a temperature adjustment mechanism.

[0076] The relationship between power and the amount of plasma raw material 101 was measured in this container member 62. Figure 5 is a graph showing the relationship between power and capacity. The horizontal axis of the graph represents the amount (capacity) of plasma raw material 101, and the vertical axis represents the percentage of the upper limit of the input power to heater 64.

[0077] The capacity on the horizontal axis is in relative volume units, and when the container 63 is filled with plasma raw material 101, the capacity is approximately 3.4. Also, because the heater 64 is controlled by PID (Proportional Integral Differential), the power supplied when it is on and when it is off actually differs greatly, but the vertical axis shows the time average of these.

[0078] In the upper graph, the average power is 9.85% when the capacity is 0 (the container 63 is empty). As the capacity increases, the average power also increases monotonically, and when the capacity is 3.4 (the container 63 is full), the average power is 12.20%. As shown in the lower graph, there is a roughly linear relationship between the capacity and the power, especially when the capacity is between 0 and 2. In other words, the results show that it is possible to calculate the amount of plasma raw material 101 using a linear relationship such as equation (1). Note that if the heater 64 is PID controlled, the average power may be used for the calculation.

[0079] It should be noted that the linear relationship breaks down when the capacity exceeds 2, but this is due to the fact that the heater 64 is placed only on the bottom, and it has been found that by placing the heater 64 on the entire surface, the relationship between the capacity and the average power approaches linearity even when the capacity exceeds 2.

[0080] The calculation unit 61 may calculate the amount of plasma raw material 101 based on the temperature detected by temperature sensor 65 and a predetermined correspondence relationship between the temperature and the amount of plasma raw material 101. Specifically, before light source device 100 is used (e.g., during manufacture), the correspondence relationships between each detected temperature and amount are recorded in advance. For example, each correspondence relationship is determined by conducting an experiment using actual container member 62, and a group of correspondence relationships is generated as a chart such as that shown in FIG. 5. The generated chart is stored in the memory of information processing device 66 and read out during calculation by calculation unit 61. Note that the correspondence relationships may also be determined by simulation rather than by actual experimentation.

[0081] Of course, calculation of quantities using formulas is included in calculation of quantities based on correspondence relationships. Alternatively, a group of correspondence relationships may be generated in other formats, such as a table. There is no limit to the number of correspondence relationships used, and correspondence relationships may be generated in any grid, such as every 0.1% of average power. Correspondence relationships may also be generated by interpolation.

[0082] As described above, in the accommodation member 62 according to this embodiment, the plasma raw material 101 is maintained in a molten state by the heater 64, and the amount of plasma raw material 101 accommodated in the accommodation vessel 63 is calculated based on the power supplied to the heater 64. This makes it possible to accurately calculate the amount of plasma raw material 101 accommodated in the accommodation vessel 63.

[0083] In an EUV light source device such as light source device 100, stable EUV light emission becomes impossible if the raw material is insufficient, so it is necessary to measure the amount of raw material in a container that supplies the raw material. In light of this, a technology is generally envisioned in which a sensor is installed inside the container to detect the amount of raw material (hereinafter referred to as the envisioned technology). In other words, the moment the liquid surface of the raw material touches the sensor, it is detected for the first time that the amount of raw material is a constant value.

[0084] However, with this assumed technology, the amount of raw material cannot be detected unless the liquid level reaches the sensor. In other words, if the liquid level is lower than the sensor position, specific information about the amount cannot be obtained.

[0085] If the specific amount is unknown, it is not clear when to discard the raw material, and it may suddenly be discovered that the storage unit 40 shown in Figure 2 is full. Also, it is not clear when to replenish the raw material, and it may suddenly be discovered that the raw material container 21 or the container in the raw material supply device 30 is empty. These problems may cause problems in the operation of the light source device 100.

[0086] While this could happen with the assumed technology, with this technology the amount of raw material is always known, making it possible to replenish or discard raw materials at the appropriate time.

[0087] Furthermore, with the assumed technology, sensing is performed by the sensor coming into direct contact with the raw material. This means that the sensor comes into contact with the high-temperature molten raw material, causing degradation. This leads to problems such as a shortened sensor lifespan. Furthermore, contaminants generated from impurities float on the liquid surface, and the contaminants adhere to the tip of the sensor, causing problems such as the amount not being detected or being detected incorrectly. In contrast, with this technology, sensing is not performed using a liquid level sensor. Therefore, there is no need for special treatments to give the sensor special heat resistance or corrosion resistance (such as coating or the use of special materials), which reduces the manufacturing costs of the device.

[0088] In addition, in the assumed technology, a sensor and a transmission line for transmitting the sensor signal to the outside are placed inside the container. Therefore, it is necessary to reserve space inside the container for the sensor itself and the transmission line, which creates the problem of the container becoming large. On the other hand, in this technology, sensing is not performed by a liquid level sensor, so there is no need to reserve space inside the container, making it possible to make the container smaller.

[0089] Furthermore, with this assumed technology, an electrical access port connected to the outside is required to transmit signals from the sensor to the outside. However, heat from within the container escapes through this port, deteriorating the container's thermal insulation. Furthermore, because this part is in contact with the outside air, there is a large temperature difference and it is prone to deterioration. This can lead to problems such as outside air leaking due to deformation or cracking. On the other hand, with this technology, sensing is not performed using a liquid level sensor, so no access port is required, making it possible to maintain high thermal insulation. Deterioration and deformation are also prevented.

[0090] In this embodiment, the amount of plasma raw material 101 is calculated based on equation (1). Therefore, as long as two pieces of information are obtained, namely the initial amount, the initial power, and the power supplied at a certain amount, it is possible to calculate the corresponding amount for any power supply thereafter. In other words, it is possible to simplify the preliminary measurement.

[0091] Furthermore, in this embodiment, the amount of plasma raw material 101 is calculated based on a predetermined correspondence relationship between the supplied power and amount. This makes it possible to accurately calculate the amount of plasma raw material 101 even when the relationship between the supplied power and amount is not linear due to factors such as a complex container shape.

[0092] In this embodiment, heater 64 is placed at the bottom of container 63. For example, evaporated plasma raw material 101 accumulates in reservoir 40 due to gravity, so plasma raw material 101 accumulates first from the bottom. By placing heater 64 at the bottom, it is possible to reliably heat plasma raw material 101 even in the early stages of accumulation.

[0093] <Second embodiment> A more detailed embodiment of the light source device 100 according to the present technology will be described as a second embodiment. In the following description, the description of the same parts as those in the configuration and operation of the light source device 100 described in the above embodiment will be omitted or simplified.

[0094] [Double structure] FIG. 6 is a schematic diagram showing an example of the configuration of a double-layered container 62. FIG. 6 shows a cross section of the container 62 in the YZ plane, viewed from the positive side in the X direction. The container 62 has a top 90, a side 91, and a bottom 92. In this example, the side 91 has a double layered structure consisting of an outer member 93, an inner member 94, and an internal space T defined between the outer member 93 and the inner member 94. In this example, the side 91 has a double layered structure around its entire periphery, but a portion of this may be single-layered, as in a typical container.

[0095] For example, if the entire side portion 91 were made of a single layer, the heat dissipation characteristics of the side portion 91 would be extremely high, and it may be necessary to use a large amount of energy to maintain the temperature of the plasma raw material 101. By making the side portion 91 a double layer, as in this example, it is possible to minimize the heat dissipation of the entire side portion 91.

[0096] This configuration is particularly effective when it is necessary to use a material with high heat dissipation properties (such as SUS, iron, aluminum, or copper) for the side portion 91. This makes it possible to select a material with low density but high heat dissipation properties, and also makes it possible to reduce the weight of the device.

[0097] In this example, the upper side of internal space T communicates with the interior of housing member 62. In Figure 6, the upper side of internal space T is open, and it communicates with the space in housing member 62 where plasma raw material 101 exists, and the space inside chamber main body 109 located above.

[0098] Of course, a configuration may be adopted in which the upper side of the internal space T is not open and the internal space T is not in communication with the inside of the housing member 62. In addition, the configurations of the outer member 93, the inner member 94, and the internal space T, such as specific shapes, are not limited.

[0099] In this example, six heaters 64 are arranged side by side in the Y direction so as to extend along the X direction, and each heater 64 is arranged so as to be embedded in the bottom 92. When the heaters 64 are embedded in the bottom 92 in this way, this also includes the heaters 64 being arranged in the bottom 92. This makes it possible to heat the plasma raw material 101 even more efficiently.

[0100] <Third embodiment> [Raw material container] FIG. 7 is a schematic diagram showing an example configuration of the plasma generation mechanism 106. FIG. 7 shows the detailed configuration of the plasma generation mechanism 106 shown in FIG. 2. In this example, a rotor 20 is immersed in the plasma raw material 101 contained in a raw material container 21. The raw material container 21 has a hollow, disk-like shape and contains the plasma raw material 101 inside. The rotor 20 has a disk-like shape that is slightly smaller than the raw material container 21, and its lower part is immersed in the plasma raw material 101 inside the raw material container 21. In FIG. 7, the raw material container 21, rotor 20, and plasma raw material 101 are shown with dashed lines. By using an LPP light source device with an immersed rotor 20 configuration like this, it is possible to efficiently generate radiation R. The raw material container 21 corresponds to one embodiment of a storage portion according to the present technology.

[0101] Furthermore, the plasma generation mechanism 106 has a cover structure 67. The cover structure 67 has a disk shape that is slightly larger than the source material container 21, and the source material container 21 and the rotor 20 are housed inside it.

[0102] Furthermore, a pipe 68 is provided on the right side of the cover structure 67. The pipe 68 is a tube for supplying the plasma raw material 101 to the raw material container 21. The pipe 68 is provided, for example, at a position above the liquid level expected during use.

[0103] Furthermore, in this technology, the heater 64 is positioned at the same height as or below the tip of the piping 68. In this example, the heater 64 is positioned on the side of the cover structure 67, approximately at the 5 o'clock position. The temperature sensor 65 is also positioned in approximately the same position as the heater 64. This is not a limitation, and the heater 64 and temperature sensor 65 may be positioned at the lowest part (6 o'clock position), for example. This allows the plasma raw material 101 to be heated efficiently, making it less likely that the plasma raw material 101 will solidify due to insufficient heating, for example. A throw-in type heater 64 may also be used. The specific positions of the heater 64 and temperature sensor 65 are not limited thereto.

[0104] When the raw material supply device 30 of FIG. 2 is not used and the configuration is completed only by the plasma generation mechanism 106, the variation shown in FIG. 7 is particularly effective.

[0105] [Layout variations] Fig. 8 is a schematic diagram showing variations in the arrangement of the heater 64 and the temperature sensor 65. Fig. 8 shows a cross section of the plasma generation mechanism 106 of Fig. 7 taken along the YZ plane at the center in the left-right direction, as viewed from the positive side in the X direction. Note that the chamber main body 109 and other components are omitted from the illustration.

[0106] In the example of FIG. 8, a space is provided inside the cover structure 67, and a motor 71 is disposed in this space. Furthermore, an opening is provided in the cover structure 67 that connects this space to the outside (the space on the right side). A rod-shaped shaft member 72 is disposed in this opening, and the motor 71 is connected to the left side of the shaft member 72, and the center of the back surface (left side surface) of the rotating body 20 is connected to the right side. The drive of the motor 71 is controlled by the control unit 107, thereby realizing the rotation of the rotating body 20. A mechanical seal 73 is provided between the opening and the shaft member 72. This allows the rotating body 20 to rotate smoothly.

[0107] An insertion port 74 is provided on the underside of the rear surface (left surface) of the cover structure 67, and the temperature sensor 65 is inserted into it. That is, while the temperature sensor 65 is arranged on the side of the cover structure 67 in FIG. 7, in this example it is arranged on the rear surface. The right end of the temperature sensor 65 faces the space in which the plasma raw material 101 exists, across the cover structure 67. Similarly, the heater 64 is arranged at the right end of the insertion port 74. That is, the heater 64 is also arranged on the rear surface.

[0108] This allows the heater 64 and temperature sensor 65 to be stably arranged. Furthermore, when the rear surface of the cover structure 67 is configured to be thick as in this example, the portion where the motor 71 is not arranged, i.e., the unused portion, can be effectively used as space for arranging the heater 64 and temperature sensor 65. This allows the device to be made more compact. Alternatively, for example, the heater 64 and temperature sensor 65 may be arranged on the surface (right surface) of the cover structure 67.

[0109] Other variations in the placement of the heater 64 and temperature sensor 65 will now be described. Typically, the heater 64 and temperature sensor 65 are placed at a position below the lower limit of the range of fluctuation in the height of the surface of the plasma raw material 101. For example, if the heater 64 and temperature sensor 65 are placed at the bottom of the container 63, the heater 64 and temperature sensor 65 will always be located below the liquid level, regardless of the height of the liquid level of the plasma raw material 101. Therefore, placing the heater 64 and temperature sensor 65 at the bottom is included in placing them at a position below the lower limit of the range of fluctuation in the liquid level. Furthermore, if multiple heaters 64 are placed, the integrated value of the power of all of them is used to calculate the amount of plasma raw material 101.

[0110] Alternatively, if it is expected that the liquid level will not fall below a certain height, the heater 64 and temperature sensor 65 may be arranged slightly below that certain height. For example, the heater 64 and temperature sensor 65 may be arranged slightly below the center. By adopting such an arrangement, the temperature of the plasma raw material 101 can be calculated with precision, enabling precise heating.

[0111] <Fourth embodiment> [Circulatory system] Fig. 9 is a schematic diagram showing a configuration example of the raw material supplying device 30. Fig. 9 shows a detailed configuration of the raw material supplying device 30 shown in Fig. 2. The raw material supplying device 30 has a storage unit 77, a heater 64, temperature sensors 65 and 79, pipes 80 and 68, a supply pipe 81, a valve 82, and a pump 83. The storage unit 77 in this example also corresponds to an embodiment of the storage unit according to the present technology.

[0112] Pipe 80 is a bent pipe, with one end connected to the lower left side of the side of storage unit 77. The other end is connected to the right side of raw material container 21 in Figure 2. This allows plasma raw material 101 to flow from the outside of storage unit 77 (raw material container 21) through the inside of pipe 80. In Figure 9, the flow direction of plasma raw material 101 is schematically shown by arrows. The piping 80 corresponds to an embodiment of the first piping according to the present technology.

[0113] Pipe 68 is also a bent pipe, with one end connected to the lower right side of the side of reservoir 77. The other end is connected to the right side of source material container 21 in Figure 2. This allows plasma raw material 101 to flow through the inside of pipe 68 and into source material container 21. The pipe 68 corresponds to an embodiment of the second pipe according to the present technology.

[0114] Supply pipe 81 is, for example, a straight pipe, and is inserted from above reservoir 77 so that one end (opening) faces the liquid surface of plasma raw material 101. Supply pipe 81 supplies plasma raw material 101 to reservoir 77.

[0115] In this technique, at least one of the pipes 80 and 68 and the supply pipe 81 has a pump that moves the plasma raw material 101. In this example, only the pipe 68 has a pump 83. The pump 83 may be any type of pump and is located midway along the pipe 68. Such a configuration for circulating the plasma raw material 101 is sometimes generally referred to as a circulation system.

[0116] The supply pipe 81 also has a valve 82. The valve 82 may be any type of valve, such as a gate valve. The valve 82 controls the movement of the plasma raw material 101.

[0117] Temperature sensor 65 is disposed on the lower side of the side of storage section 77. Temperature sensor 79 is disposed in piping 80. In this example, the driving of heater 64 is controlled based on the temperatures detected by both temperature sensors 65 and 79. This allows the driving of heater 64 to be controlled with even greater precision.

[0118] Similarly, another temperature sensor 54 may be placed in the raw material container 21 or the reservoir 40. This allows for even more accurate heating of the plasma raw material 101. Alternatively, the temperature sensor 54 may be placed in the pipe 68 or the supply pipe 81.

[0119] Alternatively, a configuration may be adopted in which the circulation system, such as piping 80, is heated by, for example, covering the circulation system with heater 64. In this case, the amount of plasma raw material 101 in the entire circulation system can be calculated using equation (1) or the like based on the total power consumed by all heaters 64.

[0120] <Fifth embodiment> [Recycling of raw materials] 10 is a schematic diagram showing an example of the configuration of a plasma generation mechanism 106 that is capable of recycling plasma raw material 101. In this example, supply pipe 81 consists of tip 86 (to the left of valve 82) and pipe section 87 (to the right or below valve 82). One end of pipe section 87 is connected to the side of reservoir 40, and the other end is connected to valve 82.

[0121] Furthermore, a pump 83 is provided in pipe section 87. When valve 82 is opened and pump 83 is driven, a flow of plasma raw material 101 is generated inside pipe section 87, and plasma raw material 101 moves from reservoir 40 to reservoir 77.

[0122] The plasma raw material 101 stored in reservoir 40 may be scattered material, and may be reusable. In this case, it may be possible to manually transfer the plasma raw material 101 from reservoir 40 to reservoir 77, but this would be a time-consuming process. By using a configuration such as that of this example, the plasma raw material 101 is automatically transferred from reservoir 40 to reservoir 77, reducing the labor required for reuse. Note that the system of this example, as well as the example shown in Figure 9, is sometimes generally referred to as a circulation system.

[0123] <Other embodiments> The present technology is not limited to the above-described embodiments, and various other embodiments can be realized.

[0124] [Type of plasma raw material] The plasma raw material 101 can be tin, lithium, gadolinium, gallium, bismuth, indium, or an alloy containing at least one of these materials.

[0125] There are no other limitations on the specific type of plasma raw material 101. For example, not only completely liquid plasma raw material 101, but also plasma raw material 101 in a liquid state mixed with solids that are in the process of melting may be used.

[0126] [Container configuration] The side of the container 63 is configured to have a thermal conductivity of, for example, 10 W / (m×k) or more and 200 W / (m×k) or less at 300 K. Alternatively, the side and bottom may be configured to have such a thermal conductivity. For example, such a thermal conductivity can be achieved by making the side and bottom from ceramic, stainless steel, or silicon.

[0127] Additionally, each component of the container 63 may be made of any material. For example, if the plasma raw material 101 is corrosive, the container 63 may be made of a corrosion-resistant material. Alternatively, the inner wall may be coated with a corrosion-resistant material. This allows for the selection of inexpensive materials.

[0128] [Application to other devices] In this example, the present technology has been described as being applied to an LPP light source device, but the present technology is not limited to this and may be applied to a DPP type or LDP type light source device. Alternatively, the present technology may be applied to a raw material container used in a device other than a light source device.

[0129] [Configuration of information processing device] The calculated amount and the detected temperature may be transmitted to an external device via a communication unit included in the information processing device 66. The amount and the detected temperature may be stored in a memory unit. The information processing device 66 may also have a display unit and an operation unit.

[0130] It is also possible to combine at least two of the above-described features of the present technology. Furthermore, the various effects described above are merely examples and are not intended to be limiting, and other effects may also be achieved. [Explanation of symbols]

[0131] EB...energy beam P...Plasma R...Radiation T…Internal space 21...Raw material container 40...Storage section 61...Calculation section 62...housing member 63...Storage container 64...Heater 65...Temperature sensor 68, 80...Plumbing 77...Storage section 91...Side 93...Outer member 94...Inner member 100...Light source device 101...Plasma raw material 107...Control unit

Claims

1. A light source device that generates radiation by converting a high temperature plasma raw material into plasma using irradiation with an energy beam, comprising: a container for the high temperature plasma raw material, a storage unit for storing the high-temperature plasma raw material; a temperature adjustment mechanism that maintains the high-temperature plasma raw material contained in the container in a molten state; a calculation unit that calculates the amount of the high-temperature plasma raw material contained in the container based on the power supplied to the temperature adjustment mechanism; A containing member comprising:

2. The housing member according to claim 1, The calculation unit calculates the amount of the high-temperature plasma raw material based on the power supplied to the temperature adjustment mechanism and a predetermined correspondence relationship between the power and the amount of the high-temperature plasma raw material. Housing member.

3. The housing member according to claim 2, The calculation unit calculates the amount of the high temperature plasma raw material based on the correspondence relationship of the following formula: Housing member. [Equation 1] V: Amount of the high-temperature plasma raw material k: a predetermined coefficient W ｘ : power supplied to the temperature adjustment mechanism W ０ : Predetermined initial power

4. The housing member according to claim 1 or 2, the temperature adjustment mechanism includes a heating mechanism that heats the high-temperature plasma raw material contained in the container, and a temperature sensor; the heating mechanism heats the high-temperature plasma raw material based on the temperature detected by the temperature sensor, thereby maintaining the high-temperature plasma raw material in a molten state; The heating mechanism and the temperature sensor are disposed at a position below the lower limit of the range of fluctuation in the height of the surface of the high-temperature plasma raw material contained in the container. Housing member.

5. The housing member according to claim 4, the container has a bottom; At least one of the heating mechanism and the temperature sensor is disposed at the bottom of the storage section. Housing member.

6. The housing member according to claim 1 or 2, A first pipe for introducing the high temperature plasma raw material from the outside and a second pipe for discharging the high temperature plasma raw material to the outside are connected to the container. Housing member.

7. The housing member according to claim 1 or 2, The housing has a side portion, At least the side portion of the storage portion has a thermal conductivity of 10 W / (m×k) or more and 200 W / (m×k) or less at 300 K. Housing member.

8. The housing member according to claim 1 or 2, The housing has a side portion, The side portion has a double structure consisting of an outer member, an inner member, and an internal space defined between the outer member and the inner member. Housing member.

9. The housing member according to claim 1 or 2, The high-temperature plasma raw material is tin, lithium, gadolinium, gallium, bismuth, indium, or an alloy containing at least one of these materials. Housing member.

10. A light source device that generates radiation by converting a high temperature plasma raw material into plasma using irradiation with an energy beam, comprising: a container for the high temperature plasma raw material, a storage unit for storing the high-temperature plasma raw material; a temperature adjustment mechanism that maintains the high-temperature plasma raw material contained in the container in a molten state; In a containing member comprising: The amount of the high-temperature plasma raw material contained in the container is calculated based on the power supplied to the temperature adjustment mechanism. Capacity calculation method.

11. A light source device that generates radiation by converting a high-temperature plasma raw material into plasma using irradiation with an energy beam, a storage unit for storing the high-temperature plasma raw material; a temperature adjustment mechanism that maintains the high-temperature plasma raw material contained in the container in a molten state; a calculation unit that calculates the amount of the high-temperature plasma raw material contained in the container based on the power supplied to the temperature adjustment mechanism; A housing member having A light source device comprising:

Images