Target material circulating system and using method thereof

Abstract

The invention belongs to the technical field of semiconductors, and discloses a target circulating system and a using method thereof. The circulating system comprises a storage assembly, a liquid inlet driving assembly, a liquid drop generator, a liquid inlet pipe, a liquid drop driving assembly, a liquid return assembly and a vacuum cavity, the storage assembly is used for storing a target material, and the storage assembly can heat the target material to be in a liquid state; the liquid inlet driving assembly comprises a first high-pressure gas cylinder and a first gas inlet pipe, and the first high-pressure gas cylinder communicates with the storage assembly through the first gas inlet pipe; the liquid drop generator is communicated with the storage assembly through a liquid inlet pipe; the liquid dropping driving assembly comprises a second high-pressure gas cylinder and a second gas inlet pipe; the second high-pressure gas cylinder is communicated with the liquid drop generator through the second gas inlet pipe; the liquid return assembly is used for collecting the target material dripped from the liquid drop generator and is communicated with the storage assembly, and at least the liquid outlet end of the liquid drop generator and at least the liquid collecting end of the liquid return assembly are located in the vacuum cavity. The circulation system and the using method thereof can save cost and prevent circulation failure of the circulation system.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a target material circulation system and a use method thereof. Background Art

[0002] In recent years, as lithography technology has rapidly developed toward finer manufacturing, semiconductor production processes have been able to produce semiconductor devices with increasingly finer feature sizes. In the next generation of semiconductor production processes, microfabrication with a feature size of 70nm to 45nm will be required, and then microfabrication with a feature size of 32nm or less will be required. For example, in order to meet the demand for microfabrication with a feature size of 32nm or less, it is expected to develop an exposure device in which a system that generates extreme ultraviolet (EUV) light with a wavelength of about 13.5nm is combined with an optical system that reduces projection reflections.

[0003] Methods for generating EUV light include, but are not necessarily limited to, converting a material having an element (e.g., xenon, lithium, or tin) into a plasma state and emitting spectral lines in the EUV range. Laser-produced plasma ("LPP") methods are usually used to bombard tin metal (in the form of droplets, plates, strips, streams, or material clusters) with a high-energy pulsed laser to form the desired plasma that can radiate EUV. For this process, the plasma is usually generated in a sealed container (e.g., a vacuum chamber) and monitored using various types of metrology equipment.

[0004] In this process, the target material can be recycled. Since the target material is in liquid state, the temperature is usually high (several hundred degrees Celsius). Using an ordinary pump body to circulate the liquid target material is very expensive and consumes a lot of energy. In addition, due to the high temperature, the magnetic pump is prone to failure, which in turn causes cycle failure.

[0005] Therefore, it is urgent to design a target material circulation system and a method of using the same to solve the above problems. Summary of the invention

[0006] An object of the present invention is to provide a target material circulation system that can save costs, reduce energy consumption, and prevent circulation failure of the circulation system.

[0007] Another object of the present invention is to provide a method for using a target material circulation system, which adopts pneumatic drive circulation, saves costs, and prolongs service life.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] Target circulation system, including:

[0010] A storage component, used for storing the target material, wherein the storage component can heat the target material to a liquid state;

[0011] A liquid inlet drive assembly, comprising a first high-pressure gas cylinder and a first air inlet pipe, wherein the first high-pressure gas cylinder and the storage assembly are connected via the first air inlet pipe;

[0012] A droplet generator and a liquid inlet pipe, wherein the droplet generator is connected to the storage assembly through the liquid inlet pipe, and the height of the first gas inlet pipe in the storage assembly is higher than the height of the liquid inlet pipe in the storage assembly, so that the gas pressure of the first high-pressure gas cylinder acts on the target material and drives the liquid target material into the droplet generator;

[0013] A droplet driving assembly, comprising a second high-pressure gas cylinder and a second air inlet pipe, wherein the second high-pressure gas cylinder and the droplet generator are connected via the second air inlet pipe;

[0014] A liquid return component and a vacuum chamber, wherein the liquid return component is used to collect the target material dripping from the droplet generator and is connected to the storage component, and at least the liquid outlet end of the droplet generator and at least the liquid collection end of the liquid return component are located in the vacuum chamber;

[0015] The first air inlet pipe, the second air inlet pipe, the liquid inlet pipe and the liquid return assembly can all be opened or cut off, and the storage assembly and the droplet generator are both provided with a pressure relief valve.

[0016] As an optional solution, the storage component includes:

[0017] A storage tank, used to store the target material, wherein one end of the first air inlet pipe away from the first high-pressure gas cylinder is inserted into the storage tank, and one end of the liquid inlet pipe away from the droplet generator is inserted into the storage tank;

[0018] A heating element is attached to the outside of the storage tank and is configured to heat the storage tank.

[0019] As an optional solution, the heating element is arranged around the circumference of the storage tank.

[0020] As an optional solution, a thermometer is provided in the storage tank.

[0021] As an optional solution, a pressure gauge is provided on the top of the storage tank.

[0022] As an optional solution, the first high-pressure gas cylinder and the second high-pressure gas cylinder are filled with inert gas.

[0023] As an optional solution, the liquid return component includes:

[0024] A liquid collecting member, disposed below the droplet generator and at least a portion of the liquid collecting member is located in the vacuum chamber;

[0025] The liquid return pipe is connected with the liquid collecting component and the storage assembly through the liquid return pipe, and the liquid return pipe can be opened or cut off.

[0026] As an optional solution, the liquid collecting member can heat the target material.

[0027] As an optional solution, the first air inlet pipe, the second air inlet pipe, the liquid inlet pipe and the liquid return pipe are all made of stainless steel; and / or

[0028] The liquid inlet pipe and the liquid return pipe are both provided with heating belts.

[0029] The method for using the target material circulation system is used to operate the target material circulation system, the pressure relief valve on the storage assembly is defined as the first pressure relief valve, the pressure relief valve on the droplet generator is defined as the second pressure relief valve, and the method for using the target material circulation system includes:

[0030] S10: the storage assembly is heated to heat the target material until it is completely melted;

[0031] S20: opening the first high-pressure gas cylinder, opening the first air inlet pipe, closing the first pressure relief valve, opening the liquid inlet pipe, opening the second pressure relief valve, the vacuum chamber is connected to the atmosphere, the target material enters the droplet generator along the liquid inlet pipe under the action of gas pressure, until the droplet generator is filled with the target material, and then cutting off the first air inlet pipe and the liquid inlet pipe;

[0032] S30: closing the second pressure relief valve, evacuating the vacuum chamber, opening the second high-pressure gas cylinder, opening the second air inlet pipe, and allowing the target material to drip from the droplet generator into the liquid return assembly under its own weight;

[0033] S40: opening the liquid return assembly and the first pressure relief valve, so that the target material in the liquid return assembly flows back into the storage assembly.

[0034] The beneficial effects of the present invention are:

[0035] The present invention provides a target material circulation system, which utilizes gas lift circulation technology to drive liquid target material from a storage component to a droplet generator through a liquid inlet drive component, and then drips the liquid target material from the droplet generator into a liquid return component through a liquid drip drive component. Specifically, the storage component is first heated to heat the target material until it is completely melted; the first high-pressure gas cylinder is opened, the first air inlet pipe is opened, the first pressure relief valve is closed, the liquid inlet pipe is opened, the second pressure relief valve is opened, the vacuum chamber is connected to the atmosphere, and the target material enters the droplet generator along the liquid inlet pipe under the action of gas pressure until the droplet generator is filled with the target material, the first air inlet pipe is cut off, and the liquid inlet pipe is cut off; then, the second pressure relief valve is closed, the vacuum chamber is evacuated, the second high-pressure gas cylinder is opened, the second air inlet pipe is opened, and the target material drips from the droplet generator to the liquid return component under its own weight; the liquid return component is opened, the first pressure relief valve is opened, and the target material in the liquid return component flows back to the storage component. The process is driven by gas, avoiding the use of electromagnetic pumps to drive high-temperature liquids. Gas drive has lower costs and consumes less energy. Compared with electromagnetic pumps, it will not come into contact with high-temperature target materials, thereby causing drive failure and cycle failure.

[0036] The present invention also provides a method for using the target material circulation system, which adopts pneumatic drive circulation, saves costs, reduces energy consumption, and prolongs the service life of the circulation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of a target material circulation system provided in an embodiment of the present invention.

[0038] In the figure:

[0039] 10. Storage assembly; 11. Storage tank; 12. Heating element; 13. Barometer; 14. Thermometer; 15. First pressure relief valve;

[0040] 20. Liquid inlet drive assembly; 21. First high-pressure gas cylinder; 22. First air inlet pipe; 221. First valve;

[0041] 30. droplet generator; 31. second pressure relief valve; 40. liquid inlet pipe; 41. second valve;

[0042] 50. dripping driving assembly; 51. second high-pressure gas cylinder; 52. second air inlet pipe; 521. third valve;

[0043] 60. Liquid return assembly; 61. Liquid collecting part; 62. Liquid return pipe; 621. Fourth valve; 70. Vacuum chamber; 80. Heating belt. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0045] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0047] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0048] This embodiment provides a target material circulation system, hereinafter referred to as the circulation system, which can save costs and prevent the circulation system from failing. Figure 1As shown, the circulation system includes a storage component 10, a liquid inlet drive component 20, a droplet generator 30, a liquid inlet pipe 40, a droplet drive component 50, a liquid return component 60 and a vacuum chamber 70. The storage component 10 is used to store a target material. The storage component 10 can heat the target material to a liquid state. For example, the target material is metallic tin. The storage component 10 heats the metallic tin to 231.9°C, and the metallic tin melts into a liquid state; the liquid inlet drive component 20 includes a first high-pressure gas cylinder 21 and a first air inlet pipe 22. The first high-pressure gas cylinder 21 and the storage component 10 are connected through the first air inlet pipe 22; the droplet generator 30 is connected to the storage component 10 through the liquid inlet pipe 40. The height of the first air inlet pipe 22 in the storage component 10 is higher than the height of the liquid inlet pipe 40 in the storage component 10, so that the first high-pressure gas cylinder 21 is connected to the storage component 10. The gas pressure of the bottle 21 acts on the target material and drives the liquid target material into the droplet generator 30. It can be understood that the liquid level of the liquid target material is between the first air inlet pipe 22 and the liquid inlet pipe 40; the droplet driving assembly 50 includes a second high-pressure gas bottle 51 and a second air inlet pipe 52, and the second high-pressure gas bottle 51 and the droplet generator 30 are connected through the second air inlet pipe 52; the liquid return assembly 60 is used to collect the target material dripping from the droplet generator 30 and is connected to the storage assembly 10, at least the liquid outlet end of the droplet generator 30 and at least the liquid collecting end of the liquid return assembly 60 are located in the vacuum chamber 70; the first air inlet pipe 22, the second air inlet pipe 52, the liquid inlet pipe 40 and the liquid return assembly 60 can all be opened or cut off, and the storage assembly 10 and the droplet generator 30 are provided with a pressure relief valve.

[0049] The pressure relief valve on the storage component 10 is defined as the first pressure relief valve 15, and the pressure relief valve on the droplet generator 30 is defined as the second pressure relief valve 31. The circulation system uses the gas lift circulation technology to drive the liquid target material from the storage component 10 to the droplet generator 30 through the liquid inlet drive component 20, and then drips the liquid target material from the droplet generator 30 into the liquid return component 60 through the droplet drive component 50. Specifically, the storage component 10 is first heated to heat the target material until it is completely melted; the first high-pressure gas cylinder 21 is opened, the first air inlet pipe 22 is opened, the first pressure relief valve 15 is closed, and the liquid inlet pipe 4 is opened. 0, open the second pressure relief valve 31, the vacuum chamber 70 is connected to the atmosphere, and the target material enters the droplet generator 30 along the liquid inlet pipe 40 under the action of gas pressure until the droplet generator 30 is filled with the target material, the first air inlet pipe 22 is cut off, and the liquid inlet pipe 40 is cut off; then, close the second pressure relief valve 31, evacuate the vacuum chamber 70, open the second high-pressure gas cylinder 51, open the second air inlet pipe 52, and the target material drips from the droplet generator 30 into the liquid return assembly 60 under the state of self-weight; open the liquid return assembly 60, open the first pressure relief valve 15, and the target material in the liquid return assembly 60 flows back to the storage assembly 10. This process uses gas for driving, avoiding the use of electromagnetic pumps and the like to drive high-temperature liquids. Gas driving has lower cost and less energy consumption. Compared with electromagnetic pumps, it will not contact with high-temperature target materials, and thus will not cause driving failure, and thus will not cause circulation failure.

[0050] Alternatively, if Figure 1 As shown, the storage assembly 10 includes a storage tank 11 and a heating element 12. The storage tank 11 is used to store target materials. The end of the first air inlet pipe 22 away from the first high-pressure gas cylinder 21 is inserted into the storage tank 11, and the end of the liquid inlet pipe 40 away from the droplet generator 30 is inserted into the storage tank 11. The heating element 12 is attached to the outside of the storage tank 11, and the heating element 12 is configured to heat the storage tank 11. Through the above configuration, the storage tank 11 is heated by the heating element 12, thereby achieving the temperature increase of the target material in the storage tank 11.

[0051] Optionally, the heating element 12 is disposed around the storage tank 11. This can improve the heating efficiency and uniformity of the storage tank 11 by the heating element 12, and ensure that the target material is heated evenly.

[0052] Optionally, a thermometer 14 is provided in the storage tank 11. Through the above arrangement, the temperature of the target material can be reasonably controlled. Further, the thermometer 14 is connected to the heating element 12 in communication. When the temperature reaches the melting point of the target material, the heating element 12 stops heating.

[0053] Optionally, a pressure gauge 13 is provided on the top of the storage tank 11 to detect the air pressure in the storage tank 11 and thereby control the speed at which the target material enters the droplet generator 30 from the liquid inlet pipe 40 .

[0054] Optionally, the first high-pressure gas cylinder 21 and the second high-pressure gas cylinder 51 are filled with inert gas to prevent the gas from reacting with the target material to produce impurities, etc. Specifically, the inert gas includes argon, helium, neon, nitrogen, hydrogen and the like, and the gas in the first high-pressure gas cylinder 21 and the second high-pressure gas cylinder 51 can be a single gas or a mixed gas, which is not limited here.

[0055] At the same time, the use of inert gas avoids contact between the target and the air, and the droplets flow in a completely sealed structure, reducing the rate at which the target is oxidized. It is understandable that the use of pumps for driving will inevitably cause agitation of the liquid target and contact with the air. This method increases the contact area between the target and the air, which can easily cause oxidation of the target to form impurities and block the droplet generator 30.

[0056] Alternatively, if Figure 1 As shown, the liquid return assembly 60 includes a liquid collection member 61 and a liquid return pipe 62. The liquid collection member 61 is disposed below the droplet generator 30 and at least a portion of the liquid collection member 61 is located in the vacuum chamber 70. The liquid collection member 61 is connected to the storage assembly 10 through the liquid return pipe 62, and the liquid return pipe 62 can be opened or cut off. The liquid collection member 61 has a certain volume, and can collect liquid for a certain period of time and then open the liquid return pipe 62 for circulation.

[0057] Optionally, the liquid collecting member 61 can heat the target material to prevent the liquid target material from solidifying during the circulation process, thereby ensuring the fluidity of the liquid and further ensuring the smoothness of the circulation.

[0058] Optionally, heating belts 80 are provided in the liquid inlet pipe 40 and the liquid return pipe 62. The heating belts 80 can heat the pipelines in which they are located, that is, the pipelines through which the liquid target material passes have a heat preservation or heating effect, ensuring that the liquid will not solidify in the pipelines and ensuring that the liquid flows smoothly in the pipelines.

[0059] Optionally, the first air inlet pipe 22 , the second air inlet pipe 52 , the liquid inlet pipe 40 and the liquid return pipe 62 are all made of stainless steel, which has relatively stable performance and is not easy to react with the target material.

[0060] Optionally, an oxide film is formed on the inner side of the liquid inlet pipe 40 and the liquid return pipe 62 , and the oxide film acts as a sealing layer on the surface of the pipe to further prevent the target material from reacting with carbon or other elements in the liquid inlet pipe 40 or the liquid return pipe 62 to generate impurities.

[0061] Alternatively, if Figure 1 As shown, a first valve 221 is provided on the first air inlet pipe 22, and the first air inlet pipe 22 is opened and closed by switching the first valve 221. Preferably, the first valve 221 is a solenoid valve, which can be switched intelligently. In other embodiments, the first valve 221 can also be a manual valve, which is not limited here.

[0062] Optionally, a second valve 41 is provided on the liquid inlet pipe 40, and the liquid inlet pipe 40 is opened and closed by switching the second valve 41. Preferably, the second valve 41 is a solenoid valve, which can be switched intelligently. In other embodiments, the second valve 41 can also be a manual valve, which is not limited here.

[0063] Optionally, a third valve 521 is provided on the second air inlet pipe 52, and the second air inlet pipe 52 is opened and closed by switching the third valve 521. Preferably, the third valve 521 is a solenoid valve, which can be switched intelligently. In other embodiments, the third valve 521 can also be a manual valve, which is not limited here.

[0064] Optionally, a fourth valve 621 is provided on the liquid return pipe 62, and the opening and closing of the liquid return pipe 62 are realized by switching the fourth valve 621. Preferably, the fourth valve 621 is a solenoid valve, which can realize intelligent switching. In other embodiments, the fourth valve 621 can also be a manual valve, which is not limited here.

[0065] This embodiment also provides a method for using the target material circulation system, which is used to operate the target material circulation system. The method includes:

[0066] S10: the storage assembly 10 heats up the target material until it is completely melted;

[0067] S20: Open the first high-pressure gas cylinder 21, open the first air inlet pipe 22, close the first pressure relief valve 15, open the liquid inlet pipe 40, open the second pressure relief valve 31, the vacuum chamber 70 is connected to the atmosphere, and the target material enters the droplet generator 30 along the liquid inlet pipe 40 under the action of gas pressure until the droplet generator 30 is filled with the target material, cut off the first air inlet pipe 22, and cut off the liquid inlet pipe 40; the liquid feeding process lasts about 1min-10min.

[0068] S30: close the second pressure relief valve 31, evacuate the vacuum chamber 70, open the second high-pressure gas cylinder 51, open the second air inlet pipe 52, and the target material drips from the droplet generator 30 into the liquid return assembly 60 under its own weight; due to the large volume of the droplet generator 30, the dripping process lasts about 10h-2000h.

[0069] S40: The liquid return assembly 60 is opened, the first pressure relief valve 15 is opened, and the target material in the liquid return assembly 60 flows back into the storage assembly 10. The liquid return process usually lasts for 1 min to 10 min.

[0070] The method for using the target material circulation system adopts pneumatic drive circulation, which saves costs, reduces energy consumption, and prolongs the service life of the circulation system.

[0071] It should be noted that the generation of extreme ultraviolet light requires the use of lasers, which is not shown in the attached drawings. This structure is a prior art and will not be described in detail here.

[0072] In addition, the outlet diameter of the droplet generator 30 is in the micrometer level, so when the target material enters the droplet generator 30 from the storage tank 11, since the vacuum chamber 70 is not evacuated at this time, the liquid's own weight is not enough to flow out from the outlet.

[0073] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A target material circulation system, characterized in that: include: A storage component (10) for storing a target material, wherein the storage component (10) is capable of heating the target material to a liquid state; A liquid inlet drive assembly (20), comprising a first high-pressure gas cylinder (21) and a first air inlet pipe (22), wherein the first high-pressure gas cylinder (21) and the storage assembly (10) are connected via the first air inlet pipe (22); a droplet generator (30) and a liquid inlet pipe (40), wherein the droplet generator (30) is connected to the storage assembly (10) through the liquid inlet pipe (40), and the height of the first gas inlet pipe (22) in the storage assembly (10) is higher than the height of the liquid inlet pipe (40) in the storage assembly (10), so that the gas pressure of the first high-pressure gas cylinder (21) acts on the target material and drives the liquid target material to enter the droplet generator (30); A liquid drop drive assembly (50), comprising a second high-pressure gas cylinder (51) and a second air inlet pipe (52), wherein the second high-pressure gas cylinder (51) and the liquid drop generator (30) are connected via the second air inlet pipe (52); a liquid return component (60) and a vacuum chamber (70), wherein the liquid return component (60) is used to collect the target material dripping from the liquid droplet generator (30) and is connected to the storage component (10), and at least the liquid outlet end of the liquid droplet generator (30) and at least the liquid collection end of the liquid return component (60) are located in the vacuum chamber (70); The first air inlet pipe (22), the second air inlet pipe (52), the liquid inlet pipe (40) and the liquid return assembly (60) can all be opened or cut off, and the storage assembly (10) and the liquid droplet generator (30) are both provided with a pressure relief valve.

2. The target material circulation system according to claim 1, characterized in that: The storage assembly (10) comprises: A storage tank (11) for storing the target material, wherein one end of the first gas inlet pipe (22) facing away from the first high-pressure gas cylinder (21) is inserted into the storage tank (11), and one end of the liquid inlet pipe (40) facing away from the droplet generator (30) is inserted into the storage tank (11); A heating element (12) is attached to the outside of the storage tank (11), and the heating element (12) is configured to heat the storage tank (11).

3. The target material circulation system according to claim 2, characterized in that: The heating element (12) is arranged around the circumference of the storage tank (11).

4. The target material circulation system according to claim 2, characterized in that: A thermometer (14) is arranged in the storage tank (11).

5. The target material circulation system according to claim 2, characterized in that: A pressure gauge (13) is provided on the top of the storage tank (11).

6. The target material circulation system according to any one of claims 1 to 5, characterized in that: The first high-pressure gas cylinder (21) and the second high-pressure gas cylinder (51) contain inert gas.

7. The target material circulation system according to any one of claims 1 to 5, characterized in that: The liquid return assembly (60) comprises: A liquid collecting member (61) is arranged below the liquid droplet generator (30) and at least a portion of the liquid collecting member (61) is located in the vacuum chamber (70); A liquid return pipe (62), the liquid collecting member (61) is connected to the storage assembly (10) via the liquid return pipe (62), and the liquid return pipe (62) can be opened or cut off.

8. The target material circulation system according to claim 7, characterized in that: The liquid collecting member (61) can heat the target material.

9. The target material circulation system according to claim 7, characterized in that: The first air inlet pipe (22), the second air inlet pipe (52), the liquid inlet pipe (40) and the liquid return pipe (62) are all made of stainless steel; and / or A heating belt (80) is disposed in both the liquid inlet pipe (40) and the liquid return pipe (62).

10. A method for using a target material circulation system, characterized in that: Used to operate the target material circulation system according to any one of claims 1 to 9, the pressure relief valve on the storage assembly (10) is defined as a first pressure relief valve (15), the pressure relief valve on the droplet generator (30) is defined as a second pressure relief valve (31), and the method for using the target material circulation system comprises: S10: the storage component (10) is heated to heat the target material until it is completely melted; S20: opening the first high-pressure gas cylinder (21), opening the first gas inlet pipe (22), closing the first pressure relief valve (15), opening the liquid inlet pipe (40), opening the second pressure relief valve (31), the vacuum chamber (70) is connected to the atmosphere, the target material enters the droplet generator (30) along the liquid inlet pipe (40) under the action of gas pressure until the droplet generator (30) is filled with the target material, and then cutting off the first gas inlet pipe (22) and the liquid inlet pipe (40); S30: closing the second pressure relief valve (31), evacuating the vacuum chamber (70), opening the second high-pressure gas cylinder (51), opening the second gas inlet pipe (52), and allowing the target material to drip from the liquid droplet generator (30) into the liquid return assembly (60) under its own weight; S40: opening the liquid return assembly (60), opening the first pressure relief valve (15), and allowing the target material in the liquid return assembly (60) to flow back into the storage assembly (10).

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