Plasma generating device for radio frequency coupling coaxial electrode discharge

Abstract

The invention relates to the technical field of plasma equipment, in particular to a radio frequency coupling coaxial electrode discharge plasma generating device which comprises a radio frequency discharge cavity, radio frequency discharge systems are arranged at the two ends of the radio frequency discharge cavity in the x-axis direction respectively, and each radio frequency discharge system is separated from the radio frequency discharge cavity through a non-shielding partition plate. One end, in the z-axis direction, of the radio frequency discharge cavity is communicated with a coaxial electrode discharge cavity, a coaxial electrode discharge system is arranged in the coaxial electrode discharge cavity, and the radio frequency discharge cavity and the coaxial electrode discharge cavity jointly define a vacuum closed cavity. According to the invention, the problem that plasma posture regulation and control are difficult to realize in a single discharge mode can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of plasma equipment, and in particular to a plasma generating device with radio frequency coupled coaxial electrode discharge. Background Art

[0002] Dust plasma is a type of plasma composed of ions, electrons, neutral gases, and solid dust particles. Dust particles can capture electrons in the plasma, becoming negatively charged, or they can be injected with electrons through an electron gun, thereby becoming negatively charged and participating in the collective behavior of the plasma. In dusty plasma, the effects of the plasma and electromagnetic forces on dust particles significantly alter many of the plasma's properties, giving rise to a host of new physical processes and phenomena, such as solitary waves, dust shocks, and dust voids.

[0003] Based on the principle of dust plasma generation, a discharge system with a single discharge mode and a vacuum chamber combination device are currently usually used to generate dust plasma. However, the single discharge mode has a small degree of freedom, and it is difficult to further realize the control of the plasma state (density, spatial distribution) on the basis of generating dust plasma. Summary of the Invention

[0004] The present invention aims to improve the problem that a single discharge mode in a plasma generating device is difficult to achieve plasma state regulation.

[0005] To solve the above problems, the present invention provides a plasma generating device using radio frequency coupled coaxial electrode discharge, comprising a radio frequency discharge cavity, wherein radio frequency discharge systems are respectively provided at both ends of the radio frequency discharge cavity along the x-axis direction, and each group of the radio frequency discharge systems is separated from the radio frequency discharge cavity by a non-shielding partition. One end of the radio frequency discharge cavity along the z-axis direction is connected to a coaxial electrode discharge cavity, and a coaxial electrode discharge system is provided in the coaxial electrode discharge cavity. The radio frequency discharge cavity and the coaxial electrode discharge cavity together form a vacuum-enclosed cavity.

[0006] Optionally, the RF discharge systems at both ends of the RF discharge cavity are symmetrically distributed, each group of the RF discharge systems includes interconnected RF coils and RF matching networks, and each of the RF coils is arranged in a planar spiral along a direction perpendicular to the x-axis.

[0007] Optionally, the coaxial electrode discharge system includes a coaxial electrode assembly and a dust box, wherein the dust box is arranged on a side of the coaxial electrode assembly away from the RF discharge cavity, and is used to inject dust particles into the coaxial electrode discharge cavity and the RF discharge cavity.

[0008] Optionally, the coaxial electrode assembly includes an annular cathode and an annular anode, the annular anode is coaxially sleeved on the outside of the annular cathode, a metal shielding cover is provided outside the coaxial electrode discharge cavity, the annular anode is connected to an external power supply, the annular cathode and the metal shielding cover are grounded, and a plurality of through holes are evenly opened on the annular cathode and the annular anode.

[0009] Optionally, the coaxial electrode discharge system further includes an electron gun, which is located on one side of the dust box and is used to charge dust particles.

[0010] Optionally, the coaxial electrode discharge system further includes a vibration component and a screening component, the screening component is located at the bottom of the dust box, and the vibration component is connected to the screening component.

[0011] Optionally, the non-shielding partition is made of transparent quartz.

[0012] Optionally, cooling cavities are provided in side walls of the radio frequency discharge cavity and the coaxial electrode discharge cavity, and a cooling medium flows in the cooling cavities.

[0013] Optionally, a mounting rail is provided in the radio frequency discharge cavity, and the mounting rail is used to install the electromagnet and / or the plasma parameter acquisition component.

[0014] Optionally, observation windows are provided at both ends of the radio frequency discharge cavity along the y-axis direction, and the other end of the radio frequency discharge cavity along the z-axis direction is connected to a vacuum pumping system.

[0015] The beneficial effects of the present invention compared to the related art include: The plasma generator of the present invention is suitable for different test environments. It adopts a dual discharge mode of radio frequency and coaxial electrodes, is compatible with the capabilities of radio frequency discharge and coaxial discharge, and can realize single-sided and double-sided radio frequency discharge. The radio frequency discharge systems at both ends can apply different powers to change the distribution of the plasma density center, thereby realizing the body shape regulation of the plasma on the basis of plasma generation. For example, the center of plasma density in the radio frequency discharge cavity will be close to the side of the radio frequency discharge system with higher power. The greater the power difference, the greater the deviation. If the same power is applied at both ends, the plasma density center is centered. Based on this plasma generator, multiple types of plasma experiments can be carried out, solving the problem of coexistence and switching of multi-mode discharge, thereby facilitating the study of plasma characteristics under the coupling of different discharge modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the external structure of a plasma generating device in an exemplary embodiment of the present invention; Figure 2is a three-dimensional cross-sectional view of a plasma generating device along the x-axis direction in an exemplary embodiment of the present invention; Figure 3 is a planar cross-sectional view of a plasma generating device along the x-axis direction in an exemplary embodiment of the present invention; Figure 4 is a top view of a coaxial electrode assembly in an exemplary embodiment of the present invention; Figure 5 FIG. 4 is a schematic structural diagram of a radio frequency coil in an exemplary embodiment of the present invention.

[0017] Explanation of the accompanying symbols: 1. RF discharge cavity; 11. Non-shielded partition; 12. Cooling cavity; 2. RF discharge system; 21. RF coil; 22. RF matching network; 3. Coaxial electrode discharge cavity; 4. Vacuuming system; 41. Vacuuming pipe; 5. Coaxial electrode discharge system; 51. Coaxial electrode assembly; 511. Annular cathode; 512. Annular anode; 513. Through hole; 52. Dust box; 53. Vibration assembly; 54. Screening assembly; 55. Electron gun; 6. Observation window; 7. Metal shielding cover; 71. Fan; 8. Flange interface; 9. Mounting rail. DETAILED DESCRIPTION

[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0019] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "multiple" means two or more.

[0020] Currently, dust plasma is typically generated using a single-discharge mode discharge system combined with a vacuum chamber. Common discharge chambers, such as the ICP (Inductively Coupled Plasma) RF discharge chamber, operate under vacuum and low pressure. The RF power generated by the ICP RF power supply is output to a toroidal coupling coil, generating a time-varying magnetic field. This magnetic field induces electrons in the coil to form eddy currents, converting electrical energy into heat. A certain proportion of mixed etching gas is then coupled to a glow discharge, generating a high-density plasma. This plasma bombards the surface of the substrate material, breaking chemical bonds. The resulting substances, which react with the etching gas, evaporate and are then extracted through vacuum lines. The resulting plasma features high density and a more uniform electron energy distribution, making it suitable for low-energy, high-density plasma processes.

[0021] Because an ICP RF discharge chamber requires an RF coil to couple energy into the plasma, the chamber is typically constructed from a large quartz structure to prevent shielding. However, quartz windows are fragile, and adding flanges to the quartz structure to trap dust can make it difficult to ensure a tight seal. Furthermore, dust injection devices typically contain metal structures such as electrodes and metal screens, and installing them directly within the RF field coupling range can interfere with the field.

[0022] The coaxial electrode discharge cavity utilizes a coaxial cylindrical electrode structure to generate a strong radial electric field in the electrode gap. When the electric field strength exceeds the breakdown threshold of the gas, the gas is ionized, forming a plasma. This cavity uses a coaxial cathode-anode-cathode configuration for DC discharge, which is suitable for forming annular or cylindrical plasma regions and for capturing dust particles. Its DC discharge is stable and it is easy to form a sheath under low pressure, which facilitates dust suspension. However, this single discharge mode still makes it difficult to achieve plasma state regulation and has limited degrees of freedom. For example, the electric field is strongest near the inner electrode, and ionization is most intense, while the electric field is weak near the outer electrode, and the plasma density is low or even in a "dark zone." This inherent radial gradient is difficult to eliminate or independently control.

[0023] Reference Figures 1 to 3 As shown, an embodiment of the present invention provides a plasma generating device with radio frequency coupled coaxial electrode discharge, including a radio frequency discharge cavity 1, wherein radio frequency discharge systems 2 are respectively provided at both ends of the radio frequency discharge cavity 1 along the x-axis direction, and each group of radio frequency discharge systems 2 is separated from the radio frequency discharge cavity 1 by a non-shielding partition 11, and one end of the radio frequency discharge cavity 1 along the z-axis direction is connected to a coaxial electrode discharge cavity 3, and a coaxial electrode discharge system 5 is provided in the coaxial electrode discharge cavity 3, and the radio frequency discharge cavity 1 and the coaxial electrode discharge cavity 3 together form a vacuum-sealed cavity.

[0024] like Figure 1 and Figure 3As shown, the plasma generating device in the embodiment of the present invention can have a four-way structure along the xy, xz, and yz planes. Taking the xz direction as an example, the RF discharge cavity 1 is located in the center, the RF discharge system 2 is installed at both ends along the x-axis, and the coaxial electrode discharge system 5 is distributed at one end along the positive z-axis. The end along the negative z-axis of the RF discharge cavity 1 can be further connected to the vacuum system 4 through a vacuum pipe 41. The RF discharge cavity 1 and the coaxial electrode discharge cavity 3 can each be in the shape of a hollow cylinder. Under the action of the vacuum system 4, the two together form a vacuum-sealed cavity. Furthermore, observation windows 6 can be provided at both ends along the y-axis of the RF discharge cavity 1. The observation windows 6 can be made of transparent quartz material for easy observation at any time. The observation windows 6 are configured as a quick-opening door structure to facilitate adjustment of the cavity interior. A detachable metal shielding cover 7 can be further installed outside the observation window 6 to reduce RF power dissipation. The metal shielding cover 7 can be removed when performing microwave diagnosis.

[0025] It should be noted that the RF discharge cavity 1 and each RF coil 21 are separated by a non-shielding partition 11. The non-shielding partition 11 physically isolates the RF discharge cavity 1 from the RF discharge system 2, preventing the RF coil 21 from directly contacting dust particles. However, the non-shielding partition 11 does not prevent the RF field of the RF discharge system 2 from coupling into the RF discharge cavity 1. Therefore, as an option, the non-shielding partition 11 can be made of transparent quartz to transmit the RF field, facilitate observation of the cavity, and form a seal within the cavity.

[0026] The plasma generator in the embodiment of the present invention adopts a dual discharge mode of radio frequency and coaxial electrodes, which is compatible with the capabilities of radio frequency discharge and coaxial discharge, and can realize single-sided and double-sided radio frequency discharge. The radio frequency discharge system 2 at both ends can apply different powers to change the distribution of the plasma density center, which is suitable for different test environments, thereby realizing the body state regulation of the plasma on the basis of generating plasma. For example, the center of the plasma density in the radio frequency discharge cavity 1 will be close to the side of the radio frequency discharge system 2 with higher power. The greater the power difference, the greater the deviation. If the same power is applied at both ends, the plasma density center is centered. Based on this plasma generator, multiple types of plasma experiments can be carried out, solving the problem of coexistence and switching of multi-mode discharge, thereby facilitating the study of plasma characteristics under the coupling of different discharge modes.

[0027] In some optional embodiments, referring to Figure 2 As shown, the coaxial electrode discharge system 5 includes a coaxial electrode assembly 51 and a dust box 52. The dust box 52 is arranged on a side of the coaxial electrode assembly 51 away from the RF discharge cavity 1 and is used to inject dust particles into the coaxial electrode discharge cavity 3 and the RF discharge cavity 1.

[0028] like Figure 2As shown, the dust box 52 can be connected to the top wall of the coaxial electrode discharge chamber 3. Dust particles can be injected into the coaxial electrode discharge chamber 3 and the RF discharge chamber 1 in sequence through the dust box 52 under the action of gravity, and then form dust plasma after discharge. In this embodiment of the present invention, by adding a port in the z-axis direction of the RF discharge chamber 1, the dust box 52 is further introduced at the same time as the coaxial electrode assembly 51, thereby avoiding direct processing on the side wall of the RF discharge chamber 1. Moreover, because the coaxial electrode assembly 51 forms a DC electric field between the electrode plates, the dust box 52 will not interfere with the coaxial electrode assembly 51, nor will it interfere with the RF discharge system 2 in the x-axis direction. Therefore, after the introduction of the dust box 52, the evolution and stability of the dust plasma and the interaction between dust particles and the background plasma can be studied, the dust plasma can be suspended and the distribution can be controlled, and the dust plasma parameters can be observed and diagnosed under different discharge mechanisms.

[0029] Further, in some optional embodiments, referring to Figure 2 and 4 As shown, the coaxial electrode assembly 51 includes an annular cathode 511 and an annular anode 512. The annular anode 512 is coaxially sleeved outside the annular cathode 511. A metal shield 7 is provided outside the coaxial electrode discharge chamber 3. The annular anode 512 is connected to an external power supply, and the annular cathode 511 and the metal shield 7 are grounded. A plurality of through holes 513 are uniformly formed on the annular cathode 511 and the annular anode 512.

[0030] Specifically, if Figure 4 As shown, the annular cathode 511 and annular anode 512 can be fixed within the coaxial electrode discharge chamber 3 via insulating ceramic. The annular cathode 511 and the metal shield 7 outside the coaxial electrode discharge chamber 3 are both grounded as a ground electrode. The annular anode 512, located between the annular cathode 511 and the metal shield 7, is connected to a power source. When the power is turned on, a strong electric field is formed between the electrodes, ionizing the gas within the electrode gap to produce plasma. Micron-sized dust particles acquire negative or positive charges through collisions in the plasma, forming charged dust particles. A large number of charged dust particles then diffuse into the discharge chamber through the through-holes 513 in the electrodes until a stable state is reached. It should be noted that the through-holes 513 in the annular cathode 511 and annular anode 512 can be small circular holes with a diameter ranging from 1 to 2 cm.

[0031] Further, refer to Figure 2 and Figure 3 As shown, the coaxial electrode discharge system 5 further includes a vibration component 53 and a screening component 54 . The screening component 54 is located at the bottom of the dust box 52 , and the vibration component 53 is connected to the screening component 54 .

[0032] like Figure 3As shown, the screening assembly 54 can specifically be a screen, which can serve as the bottom plate of the dust box 52. The screen can be sandwiched between the dust box 52 body and the aluminum plate around its bottom and fixed with screws. The vibration assembly 53 can be a variable-frequency vibration motor. The vibration motor can be installed on the side of the dust box 52, specifically within an extension box located on the side of the dust box 52. The extension box is fixed to the dust box 52 via reserved screw holes. The positive and negative poles of the vibration motor are connected through small holes in the extension box and then through a flange interface reserved in the cavity to connect to an external power supply for control. The vibration assembly 53 can drive the dust box 52 to vibrate, and the dust drop rate can be adjusted by changing the vibration frequency. In addition, a removable observation window 6 and a metal shield 7 can be provided on the top of the coaxial electrode discharge cavity 3 to facilitate real-time observation of the chamber interior and to adjust the mesh size of the sieve to adjust the dust particle size. In other embodiments, the dust may be injected by air jet or electrostatic spraying, or the dust particles may be scattered by a mechanical turntable or blades.

[0033] In some optional embodiments, referring to Figures 1 to 3 As shown, the coaxial electrode discharge system 5 further includes an electron gun 55. The electron gun 55 is located on one side of the dust box 52 and is used to charge the dust particles.

[0034] like Figure 1 As shown, multiple flange interfaces 8 can be provided on the sidewall of the coaxial electrode discharge chamber 3. The electron gun 55 can be installed at one of the flange interfaces 8, with its end extending into the coaxial electrode discharge chamber 3 and positioned below the dust box 52. The electron gun 55 can charge dust particles to facilitate their attraction to the electric field. It should be understood that multiple electron guns 55 can be provided, and other flange interfaces 8 can also be connected to components of the coaxial electrode assembly 51, such as the power supply, observation window 6, and probe.

[0035] In some optional embodiments, referring to Figure 3 and Figure 5 As shown, the RF discharge systems 2 at both ends of the RF discharge cavity 1 are symmetrically distributed. Each group of RF discharge systems 2 includes interconnected RF coils 21 and RF matching networks 22. Each RF coil 21 is arranged in a planar spiral along a direction perpendicular to the x-axis.

[0036] like Figure 3 and Figure 5 As shown, each RF coil 21 can be a hollow copper tube, wound in a planar spiral around the axial direction of the RF discharge cavity 1. Each RF coil 21 can be connected to a corresponding RF matching network 22 via a copper column. A metal shielding cover 7 is provided outside each RF coil 21, and a fan 71 can be further installed on the cover to achieve air cooling and heat dissipation.

[0037] In some optional embodiments, referring to Figure 3 As shown, a cooling cavity 12 is provided in the side walls of the radio frequency discharge cavity 1 and the coaxial electrode discharge cavity 3 , and a cooling medium flows in the cooling cavity 12 .

[0038] like Figure 3 As shown, the walls of the radio frequency discharge cavity 1 and the coaxial electrode discharge cavity 3 may be a double-layer structure, and a cooling cavity 12 is formed between the double-layer cavity walls. The cooling medium in the cooling cavity 12 may be water.

[0039] In some optional embodiments, referring to Figure 2 and Figure 3 As shown, a mounting rail 9 is provided in the radio frequency discharge cavity 1 , and the mounting rail 9 is used to install an electromagnet and / or a plasma parameter acquisition component.

[0040] Specifically, the two ends of the mounting rail 9 can be detachably connected to the side wall of the RF discharge cavity 1 by fasteners such as bolts, and the number of mounting rails 9 can be multiple, specifically 4. Different structures can be installed on the mounting rail 9 to meet test needs and realize multi-parameter synchronous measurement. For example, an electromagnet is installed to change the magnetic field distribution in the RF discharge cavity 1. Specifically, an annular electromagnet can be installed symmetrically along the axis of the RF discharge cavity 1, and its magnetic field is controlled to be distributed perpendicular to the RF coil 21. By adjusting the magnitude of the electromagnet current, the magnetic mirror effect can be studied; a strip electromagnet can also be installed in a direction parallel to the mounting rail 9, and its magnetic field can be controlled to be distributed around the electromagnet, so as to study the magnetic drift phenomenon of the plasma. In addition, plasma parameter acquisition components such as probes and invasive optical fibers can be installed on the mounting rail 9 to measure plasma parameters that cannot be directly measured at the port. In addition, a metal plate can be installed to study the distribution changes of the RF field.

[0041] Additionally, as an alternative, reference Figure 2 As shown, the sidewall of the RF discharge chamber 1 may also be provided with multiple flange interfaces 8, so that a vacuum gauge, gas circuit, diagnostic equipment, etc. can be further connected as needed. A screen can be installed at the interface between the bottom of the RF discharge chamber 1 and the vacuum system 4 to prevent dust from entering the vacuum system 4.

[0042] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A radio frequency coupled coaxial electrode discharge plasma generating device, characterized in that: The invention comprises a radio frequency discharge cavity (1), wherein radio frequency discharge systems (2) are respectively provided at both ends of the radio frequency discharge cavity (1) along the x-axis direction, each group of the radio frequency discharge systems (2) is separated from the radio frequency discharge cavity (1) by a non-shielding partition (11), one end of the radio frequency discharge cavity (1) along the z-axis direction is connected to a coaxial electrode discharge cavity (3), a coaxial electrode discharge system (5) is provided in the coaxial electrode discharge cavity (3), and the radio frequency discharge cavity (1) and the coaxial electrode discharge cavity (3) together constitute a vacuum sealed cavity.

2. The radio frequency coupled coaxial electrode discharge plasma generating device according to claim 1, characterized in that: The radio frequency discharge systems (2) at both ends of the radio frequency discharge cavity (1) are symmetrically distributed, and each group of the radio frequency discharge systems (2) comprises a radio frequency coil (21) and a radio frequency matching network (22) connected to each other, and each radio frequency coil (21) is arranged in a planar spiral along a direction perpendicular to the x-axis.

3. The radio frequency coupled coaxial electrode discharge plasma generating device according to claim 1, characterized in that: The coaxial electrode discharge system (5) comprises a coaxial electrode assembly (51) and a dust box (52); the dust box (52) is arranged on a side of the coaxial electrode assembly (51) away from the radio frequency discharge cavity (1) and is used to inject dust particles into the coaxial electrode discharge cavity (3) and the radio frequency discharge cavity (1).

4. The radio frequency coupled coaxial electrode discharge plasma generating device according to claim 3, characterized in that: The coaxial electrode assembly (51) comprises an annular cathode (511) and an annular anode (512); the annular anode (512) is coaxially sleeved on the outside of the annular cathode (511); a metal shielding cover (7) is provided outside the coaxial electrode discharge cavity (3); the annular anode (512) is connected to an external power supply; the annular cathode (511) and the metal shielding cover (7) are grounded; and a plurality of through holes (513) are uniformly provided on the annular cathode (511) and the annular anode (512).

5. The radio frequency coupled coaxial electrode discharge plasma generating device according to claim 3, characterized in that: The coaxial electrode discharge system (5) further comprises an electron gun (55), wherein the electron gun (55) is located on one side of the dust box (52), and the electron gun (55) is used to charge dust particles.

6. The radio frequency coupled coaxial electrode discharge plasma generating device according to claim 3, characterized in that: The coaxial electrode discharge system (5) further comprises a vibration component (53) and a screening component (54), wherein the screening component (54) is located at the bottom of the dust box (52), and the vibration component (53) is connected to the screening component (54).

7. The radio frequency coupled coaxial electrode discharge plasma generating device according to claim 1, characterized in that: The non-shielding partition (11) is made of transparent quartz.

8. The radio frequency coupled coaxial electrode discharge plasma generating device according to claim 1, characterized in that: A cooling cavity (12) is provided in the side walls of the radio frequency discharge cavity (1) and the coaxial electrode discharge cavity (3), and a cooling medium flows in the cooling cavity (12).

9. The radio frequency coupled coaxial electrode discharge plasma generating device according to claim 1, characterized in that: A mounting rail (9) is provided in the radio frequency discharge cavity (1), and the mounting rail (9) is used for mounting an electromagnet and / or a plasma parameter acquisition component.

10. The radio frequency coupled coaxial electrode discharge plasma generating device according to claim 1, characterized in that: Observation windows (6) are provided at both ends of the radio frequency discharge cavity (1) along the y-axis direction, and the other end of the radio frequency discharge cavity (1) along the z-axis direction is connected to a vacuum pumping system (4).

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