Grid plate for low-energy ion beam neutralization

Abstract

The invention discloses a grid plate for low-energy ion beam neutralization, and relates to the technical field of ion neutralization. The current limiting plate, the insulating ring and the neutralization plate are sequentially and coaxially connected and fixed, the front face of the current limiting plate faces the incoming flow direction of an ion beam, the neutralization plate is located on the back face of the current limiting plate, a first through hole with the diameter phi 0 is machined in the center of the current limiting plate, a second through hole with the diameter phi 1 is machined in the center of the neutralization plate, and phi 1 is larger than or equal to phi 0. A longitudinal inclination angle theta exists between the horizontal slots and the axis of the second through hole, and metal grid sheets are inserted into all the horizontal slots, so that a neutralization channel of a grid plate structure is formed in the second through hole. Energy loss and angle divergence of low-energy ion beams in the neutralization process can be reduced, the quality of neutral beams is improved, meanwhile, the structure is simple and reasonable, and the machinability of the grid plate is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of ion neutralization, in particular to a grid plate used for neutralization of low-energy ion beams. Background Art

[0002] The acquisition of neutral low-energy particle beams has attracted much attention in many industries, such as neutral particle beam etching in the semiconductor field. It is applied to the processing technology of nano-devices to avoid damage to the sample surface caused by high-energy ions and the poor focusing of low-energy ion beams. The methods of obtaining neutral particle beams usually include gas target neutralization and surface neutralization, and the principle of both is the charge exchange between charged ion beams and neutral atoms.

[0003] In the field of fusion, neutral beam injection heating is usually used to heat the plasma at the center of the tokamak. The neutral beam is generally obtained by forming a gas target through a differential pumping system. The ion beam collides with the gas target to capture or strip electrons and convert them into neutral particles. For example, the following two invention patents: a high-power long-pulse neutral beam injector vacuum chamber with application number CN201511019100.X and a gas target neutralizer with a triangular prism reflection array with application number CN201910573734.1, which introduce two different forms of neutralization target chambers. In addition, electron targets can also be used to neutralize ions, such as the following invention patent application: a positive ion neutralizer based on an electron target with application number CN202410364401.9, which uses an electron target instead of a gas target, which can reduce the gas load in the neutralizer and also reduce the gas load of the cryopump, thereby reducing the stripping loss and reionization loss of the beam. However, whether using a gas target or an electron target, the efficiency of ion exchange electron recombination is not high, and it is not suitable for the neutralization of low-energy ions.

[0004] In addition, in the preparation technology of high-flux neutral atom beam with application number CN97105079.1, a high atomic number metal plate with negative bias is used as a neutralization target, and the ion beam is neutralized based on the surface neutralization principle. The atomic number of the metal plate is more than 30 larger than the atomic number of the incident particle. This ion neutralization method is usually used in the technology of obtaining atomic oxygen; a high-flux neutral atomic oxygen beam generation system and generation method with application number CN202211559321.6 can obtain high-flux low-energy neutral particles, but the reflection angle is too large, and the ion energy loss is relatively serious. Moreover, the plasma beam is neutralized, and ions and electrons are not distinguished. The neutral particle beam is impure and the beam quality is poor.

[0005] The application number CN201110289007.6 is a mesh plate structure for ion neutralization, which proposes a mesh plate with a mesh structure. By setting the thickness of different areas of the mesh plate, the density distribution of the neutral particle beam in different areas is adjusted. The application number CN202110279321.X is a particle beam device and a composite beam device, which proposes a charge exchange grid, which adopts a concave curved cylindrical structure that gradually contracts and then expands, and a multiple cylindrical deformation structure, to improve the efficiency of neutralization. In the process of surface neutralization, the roughness of the ion glancing surface is a very critical parameter. The smaller the surface roughness, the smaller the scattering of the neutral particles after the charge exchange, and at the same time, it has a higher neutralization efficiency. However, whether it is a mesh structure or a cylindrical structure, it is difficult to manufacture in order to obtain a neutralization channel with a lower roughness. Summary of the invention

[0006] In order to solve the shortcomings of the background technology, the present invention provides a grid plate for neutralizing low-energy ion beams, which can reduce the energy loss and angular divergence of low-energy ion beams during the neutralization process and improve the quality of the neutral beam. At the same time, its structure is simple and reasonable, ensuring the machinability of the grid plate.

[0007] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a grid plate for neutralizing a low-energy ion beam, comprising a current limiting plate, an insulating ring and a neutralizing plate, wherein the current limiting plate, the insulating ring and the neutralizing plate are coaxially connected and fixed in sequence, the front side of the current limiting plate faces the incoming direction of the ion beam, the neutralizing plate is located on the back side of the current limiting plate, a first through hole is processed at the center of the current limiting plate, the diameter of the first through hole is Φ0=10mm~15mm, a second through hole is processed at the center of the neutralizing plate, the diameter of the second through hole is Φ1=10mm~20mm, and Φ1≥Φ0, a plurality of horizontal slots are uniformly processed along the longitudinal direction on the front side of the neutralizing plate, a longitudinal inclination angle θ exists between the horizontal slot and the axis of the second through hole, θ=3°~5°, and metal grids are inserted in all the horizontal slots to form a neutralization channel of a grid plate structure in the second through hole, and the roughness R of the metal grid is a =1nm~10nm.

[0008] Furthermore, a lead connector is provided on the surface of the neutralization plate to connect a picoammeter to measure the magnitude of the neutralization current.

[0009] Furthermore, the metal grid is divided into two forms: a single-angle arrangement and a tapered-angle arrangement. The single-angle arrangement means that the longitudinal inclination angles and directions of all horizontal slots are the same and are arranged at equal intervals, so that all metal grids are finally arranged at equal intervals with a single inclination in the same direction; the tapered-angle arrangement means that all horizontal slots are divided into two parts of equal number, and the longitudinal inclination angles of the two parts of the horizontal slots are the same but in different directions, and are arranged symmetrically up and down along the axis of the first through hole, so that every two symmetrical metal grids form a tapered arrangement with a wide front end and a narrow rear end.

[0010] Furthermore, the current limiting plate is made of molybdenum and has a thickness of 0.5 mm to 2 mm.

[0011] Furthermore, the neutralizing plate is made of 316L stainless steel and has a thickness of 0.7 mm to 15 mm.

[0012] Furthermore, the insulating ring is made of polytetrafluoroethylene and has a thickness of 0.5 mm to 1 mm.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: based on the principle of surface neutralization, the present invention uses a metal grid with a low surface roughness as the core part of the neutral plate, which can reduce the energy loss and angle divergence of the low-energy ion beam during the neutralization process to improve the quality of the neutral beam. At the same time, its structure is simple and reasonable, ensuring the machinability of the grid. In addition, the neutralization efficiency can be evaluated online by measuring the current on the neutralization plate. Based on this structure, the ion beam neutralization efficiency of more than 98% can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a rear view of the grid plate of the present invention;

[0015] Figure 2 is a front view of the current limiting plate of the present invention;

[0016] Figure 3 is a three-dimensional schematic diagram of a neutralized plate of the present invention;

[0017] Figure 4 It is a side view of the grid plate of the present invention arranged in a single inclination angle;

[0018] Figure 5 It is a side view of the grid plate of the present invention which is arranged in a tapered inclination.

[0019] In the figure: 1. Current limiting plate; 2. Insulating ring; 3. Neutralizing plate; 4. Lead connector; 5. Metal grid. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] like Figure 1 to Figure 5 As shown, a grid plate for neutralizing a low-energy ion beam comprises a current limiting plate 1, an insulating ring 2 and a neutralizing plate 3.

[0022] Combination Figure 1 As shown, the current limiting plate 1, the insulating ring 2 and the neutralizing plate 3 are coaxially connected and installed in sequence and fixed by screws and insulating gaskets, wherein the front side of the current limiting plate 1 faces the incoming direction of the ion beam, the neutralizing plate 3 is located on the back side of the current limiting plate 1, and the insulating ring 2 is clamped between the current limiting plate 1 and the neutralizing plate 3 to ensure insulation between the current limiting plate 1 and the neutralizing plate 3.

[0023] Combination Figure 2 As shown, the current limiting plate 1 is made of a metal material with a low sputtering rate, such as molybdenum, and has a thickness of 0.5 mm to 2 mm. A first through hole is processed at the center of the current limiting plate 1, and the diameter of the first through hole is Φ0 = 10 mm to 15 mm, which is used to control the flux of the ion beam entering the neutralization plate 3.

[0024] Combination Figure 3 As shown, the neutralization plate 3 is made of a metal material with good processing performance and conductive properties, such as 316L stainless steel, and its thickness is 0.7mm~15mm. A second through hole is processed at the center position of the neutralization plate 3, and the diameter of the second through hole is Φ1=10mm~20mm, and Φ1≥Φ0. A lead connector 4 is set on the surface of the neutralization plate 3 for connecting a picoammeter to measure the magnitude of the neutralization current. A plurality of horizontal slots are uniformly processed along the longitudinal direction on the front side of the neutralization plate 3, and there is a longitudinal inclination angle θ between the horizontal slot and the axis of the second through hole, θ=3°~5°, and metal grids 5 are inserted in all horizontal slots to form a neutralization channel of a grid structure in the second through hole, and the roughness R of the metal grid 5 is a =1nm~10nm, when ions are injected into the neutralization channel, grazing collision and neutralization can occur on the surface of the metal grid 5. Among them, the metal grid 5 can be arranged in two forms: a single inclination angle arrangement and a tapered inclination angle arrangement:

[0025] Combination Figure 4 As shown, the single-angle arrangement means that the longitudinal inclination angles and directions of all horizontal slots are the same and arranged at equal intervals, so that all metal grids 5 are finally arranged at equal intervals at a single inclination angle in the same direction;

[0026] Combination Figure 5 As shown, the tapered arrangement means that all horizontal slots are divided into two parts of equal number, the longitudinal inclination angles of the two parts of the horizontal slots are the same but in different directions, and they are arranged symmetrically up and down along the axis of the first through hole, so that finally every two symmetrical metal grids 5 form a tapered arrangement with a wide front end and a narrow rear end.

[0027] The insulating ring 2 is made of an insulating material with a low outgassing rate, such as polytetrafluoroethylene, and has a thickness of 0.5 mm to 1 mm. In order to adapt to the connection between the limiting plate 1 and the neutralizing plate 3 without affecting the neutralizing channel, the insulating ring 2 can be set to a rectangle with an edge slightly larger than the neutralizing plate 3, and the center is set to a through hole slightly larger than the diameter of the second through hole.

[0028] The working principle is: the front of the current limiting plate 1 faces the incoming direction of the ion beam, and the axis of the ion beam is incident along the normal direction of the current limiting plate 1. The current limiting plate 1 and the neutralizing plate 3 are grounded, and the neutralizing plate 3 is connected to the picoammeter through the lead connector 4. Assume that the flux density of the ion beam at the first through hole position of the current limiting plate 1 is Then the ion flux incident on the neutralization plate 3 and participating in the neutralization reaction is Inside the neutralization plate 3, there is a certain probability that the ions in the neutralization channel will collide with the surface of the metal grid 5 to exchange charges, take away electrons and become neutral atoms, forming a neutralization current I. The ion flux η2=6.25×10 18 I, therefore, the neutralization efficiency can be obtained

[0029] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms of assembly without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0030] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A grid plate for neutralizing a low-energy ion beam, characterized in that: The invention comprises a current limiting plate (1), an insulating ring (2) and a neutralizing plate (3), wherein the current limiting plate (1), the insulating ring (2) and the neutralizing plate (3) are coaxially connected and fixed in sequence, the front face of the current limiting plate (1) faces the incoming direction of the ion beam, the neutralizing plate (3) is located at the back face of the current limiting plate (1), a first through hole is processed at the center of the current limiting plate (1), the diameter of the first through hole is Φ0=10mm-15mm, a second through hole is processed at the center of the neutralizing plate (3), the diameter of the second through hole is Φ1=10mm-20mm, and Φ1≥Φ0, a plurality of horizontal slots are uniformly processed along the longitudinal direction on the front face of the neutralizing plate (3), a longitudinal inclination angle θ is formed between the horizontal slot and the axis of the second through hole, θ=3°-5°, and metal grids (5) are inserted in all the horizontal slots to form a neutralizing channel of a grid plate structure in the second through hole, and the roughness R of the metal grid (5) is a =1nm~10nm.

2. A grid plate for neutralizing a low-energy ion beam according to claim 1, characterized in that: A lead connector (4) is arranged on the surface of the neutralization plate (3) to connect to a picoammeter to measure the magnitude of the neutralization current.

3. A grid plate for neutralizing a low-energy ion beam according to claim 1 or 2, characterized in that: The metal grids (5) are divided into two forms: a single-angle arrangement and a tapered-angle arrangement. The single-angle arrangement means that the longitudinal inclination angles and directions of all horizontal slots are the same and are arranged at equal intervals, so that all metal grids (5) are arranged at equal intervals at a single inclination in the same direction. The tapered-angle arrangement means that all horizontal slots are divided into two equal parts, the longitudinal inclination angles of the two parts of the horizontal slots are the same but in different directions, and are arranged symmetrically up and down along the axis of the first through hole, so that every two symmetrical metal grids (5) form a tapered arrangement with a wide front end and a narrow rear end.

4. The grid plate for neutralizing a low-energy ion beam according to claim 1, characterized in that: The current limiting plate (1) is made of molybdenum and has a thickness of 0.5 mm to 2 mm.

5. The grid plate for neutralizing a low-energy ion beam according to claim 1, characterized in that: The neutralizing plate (3) is made of 316L stainless steel and has a thickness of 0.7 mm to 15 mm.

6. The grid plate for neutralizing a low-energy ion beam according to claim 1, characterized in that: The insulating ring (2) is made of polytetrafluoroethylene and has a thickness of 0.5 mm to 1 mm.

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