A grid for neutralization of low-energy ion beams

Abstract

A grid plate for low-energy ion beam neutralization relates to the technical field of ion neutralization. The flow limiting plate, the insulating ring and the neutralization plate are coaxially connected and fixed in sequence. The front surface of the flow limiting plate faces the direction of the ion beam flow. The neutralization plate is located at the back surface of the flow limiting plate. The first through hole with a diameter of Φ0 is processed in the center of the flow limiting plate. The second through hole with a diameter of Φ1 is processed in the center of the neutralization plate, and Φ1≥Φ0. The front surface of the neutralization plate is uniformly processed with a plurality of horizontal slots in the longitudinal direction. There is a longitudinal inclination angle θ between the horizontal slot and the axis of the second through hole. Metal grid plates are inserted into all the horizontal slots to form a neutralization channel with a grid plate structure in the second through hole. The energy loss and angular divergence of the low-energy ion beam during the neutralization process can be reduced, and the quality of the neutral beam can be improved. At the same time, the structure is simple and reasonable, and the machinability of the grid plate is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ion neutralization, and particularly relates to a grid plate for neutralizing low-energy ion beams. BACKGROUND

[0002] The acquisition of neutral low-energy particle beams is of great concern in many industries, such as neutral particle beam etching in the semiconductor field, which is applied to the processing technology of nanometer devices and can avoid damage to the sample surface caused by high-energy ions and the poor focusing of low-energy ion beams. The ways to obtain neutral particle beams usually include gas target neutralization and surface neutralization, and the principle of both is the charge exchange between the charged ion beam and the neutral atoms.

[0003] In the field of fusion, the plasma at the center of a tokamak is usually heated by neutral beam injection. The way to obtain neutral beams is generally to form a gas target through a differential pumping system, and the ion beam collides with the gas target to capture or strip electrons to convert into neutral particles, for example, the following two granted patents: a high-power long-pulse neutral beam injector vacuum chamber with application number CN201511019100.X and a gas target neutralizer with a three-prism reflection array with application number CN201910573734.1, which introduce two different forms of neutralization target chambers. In addition, an electron target can also be used to neutralize ions, for example, the following invention patent application: a positive ion neutralizer based on an electron target with application number CN202410364401.9, which uses an electron target to replace a gas target, which can reduce the gas load in the neutralizer and also reduce the gas load of the cryogenic pump, achieving the effect of reducing beam stripping loss and re-ionization loss. However, whether a gas target or an electron target is used, 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, the preparation technology of high-flux neutral atom beam with application number CN97105079.1 uses a high-atomic-number metal plate with a negative bias as a neutralization target based on the principle of surface neutralization, and the atomic number of the metal plate is more than 30 greater than that of the incident particles. This ion neutralization method is usually used in the technology of obtaining atomic oxygen; a high-flux neutral atomic oxygen beam generation system and method with application number CN202211559321.6 can obtain high-flux low-energy neutral particles, but the reflection angle is too large, causing serious ion energy loss, and the method is used to neutralize the plasma beam without distinguishing between ions and electrons, resulting in impure neutral particle beams and poor beam quality.

[0005] And the application number for CN201110289007.6 a net board structure for ion neutralization, it proposes a net board with mesh structure, by setting the thickness of different regions of the net board, adjust the density distribution of neutral particle beam in different regions, application number CN202110279321.X particle beam device and composite beam device, it proposes a charge exchange grid, using tapered rear expansion of the concave surface cylinder structure and multiple cylinder deformation structure, for improving the efficiency of neutralization. In the process of surface neutralization, ion grazing the roughness of the surface is a very critical parameter, the smaller the surface roughness, the smaller the scattering of neutral particles after charge exchange, at the same time has higher neutralization efficiency. However, whether it is mesh structure or cylinder structure, to obtain a lower roughness neutralization channel, in processing has great manufacturing difficulty. SUMMARY

[0006] To solve the problems in the background art, the present application provides a grid plate for low energy ion beam neutralization, which can reduce the energy loss and angular divergence of low energy ion beam in the process of neutralization, improve the quality of neutral beam, and at the same time, its structure is simple and reasonable, which ensures the processability of the grid plate.

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

[0008] Further, the neutralization plate surface is provided with a lead connector to connect a picoammeter to measure the size of the neutralization current.

[0009] Further, the metal grid is divided into two forms of single inclination angle arrangement and inclination angle tapering arrangement, the single inclination angle arrangement refers to that the longitudinal inclination angle and direction of all horizontal slots are same and arranged at equal intervals, finally all metal grids are arranged at equal intervals with single inclination angle in the same direction, the inclination angle tapering arrangement refers to that all horizontal slots are divided into two parts with same quantity, the longitudinal inclination angle of two parts of horizontal slots is same but the direction is different, the two parts are arranged symmetrically along the axis of the first through hole, finally every two symmetric metal grids form tapering arrangement with wide front end and narrow rear end.

[0010] Further, the flow limiting plate is made of molybdenum, and the thickness is 0.5mm-2mm.

[0011] Further, the neutralization plate is made of 316L stainless steel, and the thickness is 0.7mm-15mm.

[0012] Further, the insulating ring is made of polytetrafluoroethylene, and the thickness is 0.5mm-1mm.

[0013] Compared with the prior art, the beneficial effects of the present application are as follows: based on the principle of surface neutralization, the metal grid with low surface roughness is used as the core part of the neutralization plate, the energy loss and angle divergence of the low-energy ion beam in the neutralization process can be reduced, the quality of the neutral beam is improved, meanwhile, the structure is simple and reasonable, and the processability of the grid plate is ensured. In addition, the online evaluation of the neutralization efficiency can be realized by measuring the current on the neutralization plate, and the ion beam neutralization efficiency of more than 98% can be realized based on the structure. BRIEF DESCRIPTION OF DRAWINGS

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

[0015] Figure 2 is the front view of the flow limiting plate of the present application;

[0016] Figure 3 is the three-dimensional schematic view of the neutralization plate of the present application;

[0017] Figure 4 is the side view of the grid plate of the present application adopting single inclination angle arrangement;

[0018] Figure 5 is the side view of the grid plate of the present application adopting inclination angle tapering arrangement.

[0019] In the figure: 1, flow limiting plate; 2, insulating ring; 3, neutralization plate; 4, lead connector; 5, metal grid. DETAILED DESCRIPTION

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] like Figures 1-5 As shown, a grid plate for neutralizing low-energy ion beams includes a current-limiting plate 1, an insulating ring 2, and a neutralization 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 are fixed by screws and insulating washers. The front of the current limiting plate 1 faces the direction of the ion beam flow, the neutralizing plate 3 is located on the back 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 the 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 low sputtering rate metal material, such as molybdenum, with a thickness of 0.5 mm to 2 mm. A first through hole is machined at the center of the current limiting plate 1, with a diameter 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 and electrical conductivity, such as 316L stainless steel, with a thickness of 0.7mm to 15mm. A second through hole is machined at the center of the neutralization plate 3, with a diameter Φ1 = 10mm to 20mm and Φ1 ≥ Φ0. A lead wire connector 4 is provided on the surface of the neutralization plate 3 for connecting a picoammeter to measure the neutralization current. Several horizontal slots are uniformly machined longitudinally on the front side of the neutralization plate 3. There is a longitudinal inclination angle θ between the horizontal slots and the axis of the second through hole, θ = 3° to 5°. Metal grid plates 5 are inserted into all horizontal slots to form a grid-structured neutralization channel within the second through hole. The roughness R of the metal grid plates 5 is... a =1nm~10nm, when ions are injected into the neutralization channel, they can undergo grazing collision neutralization on the surface of the metal grid 5. The metal grid 5 can be arranged in two forms: a single-angle arrangement and a gradually decreasing-angle arrangement.

[0025] Combination Figure 4 As shown, the tilt angle single arrangement means that the longitudinal tilt angle and direction of all horizontal slots are the same and they are arranged at equal intervals, so that all metal grids 5 are arranged at equal intervals with a single tilt angle in the same direction.

[0026] CombinationFigure 5 As shown, the tapering arrangement refers to that all horizontal slots are divided into two parts of equal number, the longitudinal inclination angles of the two parts of horizontal slots are the same but the directions are different, and the two parts are arranged symmetrically along the axis of the first through hole, so that each two symmetrical metal grating 5 forms a tapering arrangement with the front end wide and the rear end narrow.

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

[0028] The working principle is: the front surface of the current limiting plate 1 faces the ion beam flow direction, so that the ion beam axis is incident along the normal direction of the current limiting plate 1, the current limiting plate 1 and the neutralization plate 3 are grounded, and the neutralization plate 3 is connected to the picoammeter through the lead connector 4. Assuming that the flux density of the ion beam at the position of the first through hole of the current limiting plate 1 is Then the ion flux incident on the neutralization plate 3 participating in the neutralization reaction is In the neutralization plate 3, the ions have a certain probability of glancing collision with the surface of the metal grating 5 in the neutralization channel to exchange charges, take away electrons to become neutral atoms, form a neutralization current I, and the ion flux η2 participating in the neutralization reaction can be obtained as 6.25x10 18 I, therefore, the neutralization efficiency can be obtained as

[0029] It is apparent for a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but can be implemented in other embodiments without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the application being defined by the appended claims rather than by the above description, and it is intended to embrace all changes and modifications that fall within the meaning and scope of equivalents of the claims. Any reference signs in the claims should not be construed as limiting the claims to the figures in which the reference signs are used.

[0030] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be properly combined to form other embodiments that those skilled in the art can understand.

Claims

1. A grid plate for neutralization of low energy ion beams, characterized in that: The device includes a current-limiting plate (1), an insulating ring (2), and a neutralization plate (3). The current-limiting plate (1), the insulating ring (2), and the neutralization plate (3) are coaxially connected and fixed in sequence. The front of the current-limiting plate (1) faces the direction of the ion beam flow, and the neutralization plate (3) is located on the back of the current-limiting plate (1). The insulating ring (2) is sandwiched between the current-limiting plate (1) and the neutralization plate (3). A first through hole is machined at the center of the current-limiting plate (1), and the diameter of the first through hole is... A second through hole is machined at the center of the neutralization plate (3), and the diameter of the second through hole is... ,and The insulating ring (2) is set as a rectangle with an edge slightly larger than that of the neutralizing plate (3), and the center is set as a through hole with a diameter slightly larger than that of the second through hole. Several horizontal slots are uniformly machined along the longitudinal direction on the front side of the neutralizing plate (3), and there is a longitudinal inclination angle between the horizontal slots and the axis of the second through hole. , Furthermore, metal grids (5) are inserted into all horizontal slots to form neutral channels with a grid structure within the second through holes, wherein the roughness of the metal grids (5) is... R a = For 1nm~10nm, the metal grids (5) are divided into two types: single-angle arrangement and tapered-angle arrangement. The single-angle arrangement means that the longitudinal angle and direction of all horizontal slots are the same and they are arranged at equal intervals, so that all metal grids (5) are arranged at equal intervals with a single angle in the same direction. The tapered-angle arrangement means that all horizontal slots are divided into two equal parts, the longitudinal angle of the two parts of horizontal slots are the same but the direction is different, and they are arranged symmetrically up and down along the axis of the first through hole, so that each pair of symmetrical metal grids (5) forms a tapered arrangement with a wide front end and a narrow back end.

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

3. A grid for neutralization of low energy ions as defined in claim 1, characterized in that: The flow limiting plate (1) is made of molybdenum and has a thickness of 0.5mm-2mm.

4. A grid for neutralization of low energy ions as defined in claim 1, characterized in that: The neutralization plate (3) is made of 316L stainless steel and has a thickness of 0.7mm-15mm.

5. A grid for neutralization of low energy ions as defined in claim 1, characterized in that: The insulation ring (2) is made of polytetrafluoroethylene and has a thickness of 0.5mm-1mm.

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