Ion beam focusing system

Abstract

The invention discloses an ion focusing system which comprises a process chamber, and a beam ion source, an electric lens assembly and a bearing platform which are sequentially arranged in the process chamber from top to bottom, the process chamber is grounded; the electric lens assembly comprises a plurality of infinitesimal electric lenses, and the plurality of infinitesimal electric lenses are spliced to form an electric lens array; the electric lens array is a curved surface which is bent downwards and is in a rotationally symmetrical pattern; the electric lens assembly is connected with a first negative pressure V1; the bearing platform is connected with a second negative pressure V2 so as to form an electric field between the bearing platform and the electric lens assembly, and V2 < V1 < 0; after plasma generated by the beam ion source passes through the electric lens assembly, positive ions in the plasma are focused to the central area of the electric lens assembly under the action of an electric field, and the central area is a circular area which takes the rotating shaft as the center and is located on the bearing platform. According to the ion focusing system based on the calculus idea, the focusing effect of ions can be improved, and the diameter of the focused ion beam can be within 10 mm.

Description

Technical Field

[0001] The present application relates to the field of micro-machining technology, and in particular to an ion beam focusing system. Background Art

[0002] Ion beam-based additive manufacturing technology can directly write structures and patterns on materials without external heat sources, thereby significantly reducing the stress of the prepared materials. However, large beam current ion beams are generally divergent and are severely pulled by electrons in the beam, making them difficult to focus.

[0003] Magnetic lens is one of the commonly used focusing methods. It can focus a large beam of ion current by confining electrons to pull ions. However, since the Lorentz force does not do work, the magnetic lens cannot provide energy to the ions, resulting in poor stability of the ion beam after passing through the magnetic lens. Once momentum exchange occurs with the background gas, it may diverge again. Therefore, the focusing effect of the magnetic lens on a large beam of ion current is limited. Summary of the invention

[0004] In response to the above technical problems, the present application provides an ion beam focusing system, which can improve the problem that the existing magnetic lens cannot provide momentum to ions, so that the ions may diverge again due to collision after passing through the magnetic lens.

[0005] To solve the above technical problems, in a first aspect, an embodiment of the present application provides an ion beam focusing system, comprising a process chamber, and a beam ion source, an electric lens assembly and a carrying platform arranged in sequence from top to bottom in the process chamber;

[0006] The process chamber is grounded;

[0007] The electric lens assembly includes a plurality of micro-element electric lenses, which are spliced ​​to form an electric lens array; the electric lens array is a downward curved surface and a rotationally symmetrical figure; the electric lens assembly is connected to a first negative pressure V1;

[0008] The carrying platform is connected to a second negative voltage V2 to form an electric field with the electric lens assembly, and V2<V1<0;

[0009] After the plasma generated by the beam ion source passes through the electric lens assembly, the positive ions therein are focused toward the central area of ​​the electric lens assembly under the action of the electric field. The central area is a circular area centered on the rotation axis and located on the supporting platform.

[0010] Optionally, the longitudinal cross section of the electric lens array is formed by connecting one or more of a circular arc, an elliptical arc, a hyperbola segment, a parabola segment, and a straight line segment; or,

[0011] The longitudinal cross section of the electric lens array is formed by connecting one or more of a circular arc, an elliptical arc, a hyperbola segment, and a parabola segment with a straight line segment.

[0012] Optionally, the longitudinal cross-section of the electric lens array is arc-shaped; and;

[0013] The curvature of the electric lens array is 0 to 100 m -1 ; and / or, the diameter of the projection of the electric lens array on a plane perpendicular to the axial direction is 5 to 200 mm.

[0014] Optionally, the aperture of the microelement electric lens is greater than or equal to 0.001 mm and less than or equal to the thickness s of the plasma sheath. 0 twice of which,

[0015]

[0016] Where V 0 is the potential of the microelement electric lens, T e is the electron temperature, is the electron Debye length.

[0017] Optionally, the aperture of the micro-element electric lens is 0.001-10 mm; and / or,

[0018] The hole spacing between two adjacent micro-element electric lenses is 0.001-10 mm.

[0019] Optionally, the ion beam focusing system further includes a process chamber, the beam ion source, the electric lens assembly and the supporting platform are arranged in the process chamber, and the process chamber is grounded.

[0020] Optionally, the distance between the electric lens assembly and the beam ion source is 10 to 300 mm; and / or,

[0021] The distance between the lower end of the electric lens assembly and the carrying platform is 10 to 300 mm.

[0022] Optionally, at least two electric lens assemblies are provided and are arranged in sequence from the ion source to the supporting platform to form multi-stage focusing.

[0023] Optionally, the ion beam processing equipment further comprises a magnetic lens disposed in the process chamber;

[0024] The magnetic lens is arranged around the outer side of the carrying platform and the electric lens assembly.

[0025] Optionally, the magnetic field strength of the magnetic lens gradually increases from top to bottom.

[0026] As described above, in the ion focusing system of the present application, the electric lens assembly includes a plurality of micro-element electric lenses, all of which are spliced ​​to form an electric lens array, the electric lens array is a rotationally symmetrical figure, the electric lens assembly and the carrying platform are respectively loaded with negative pressures V1 and V2, and V2<V1<0, so that an electric field is formed between the carrying platform and the electric lens assembly. Based on the idea of ​​calculus, the present application regards an irregular large beam current ion beam as a large number of uniform micro-element parallel ion beams, and sets a corresponding micro-element electric lens for each micro-element parallel ion beam. When the plasma passes through the hole of the micro-element electric lens, the electrons therein are repelled and the positive ions are attracted to pass through, so that a micro-element pure ion beam can be obtained. Since the positive ions passing through the electric lens assembly can be focused to the central area of ​​the electric lens assembly under the action of the electric field, all micro-element pure ion beams are focused to the central area of ​​the electric lens assembly. In addition, since the electric lens array is a downward curved surface, the shape can change the initial velocity and force direction of the positive ions when passing through the micro-element electric lens, strengthen the movement of the ions to the central area, and the diameter of the ion beam after focusing can reach less than 10 mm, breaking through the limitations of the original technology. Therefore, the ion focusing system of the present application can eliminate electronic interference and at the same time strengthen the movement of ions toward the central area based on the curved surface shape of the electric lens array, thereby improving the focusing effect of ions, that is, obtaining a smaller focusing radius. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application. In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor.

[0028] Figure 1 It is a schematic diagram of the focusing principle of an existing electric lens;

[0029] Figure 2 is a structural schematic diagram of an ion beam focusing system provided in an embodiment of the present application;

[0030] Figure 3 It is a partial structural schematic diagram of an electric lens assembly provided in an embodiment of the present application;

[0031] Figure 4 1 is a schematic diagram of the motion of a charged particle provided in an embodiment of the present application, wherein (a) is a schematic diagram of the motion of a charged particle in a sheath fusion state, (b) is a simulation result of the motion of an electron in the sheath, and (c) is a simulation result of the motion of an ion in the sheath;

[0032] Figure 5: is a simulation diagram of the process effect of the ion beam focusing system provided in the embodiment of the present application, wherein (a) is an ion density distribution diagram; (b) is a deposition flux curve of ions on a substrate, (r=0 mm is the symmetry axis Z);

[0033] Figure 6 Schematic diagram of an electric lens assembly provided by an embodiment of the present application, wherein (a) is a bottom view, (b) is a cross-sectional view along line AA in (a), and (c) is a partial view;

[0034] Figure 7 is a schematic structural diagram of another ion beam focusing system provided in an embodiment of the present application;

[0035] Figure 8 It is a structural schematic diagram of another ion beam focusing system provided in an embodiment of the present application.

[0036] The realization of the purpose, functional features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. The above-mentioned drawings have shown clear embodiments of this application, which will be described in more detail later. These drawings and textual descriptions are not intended to limit the scope of the concept of this application in any way, but to illustrate the concept of this application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0037] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0038] It should be further understood that the terms "comprising" and "including" indicate the presence of the described features, steps, operations, elements, components, items, kinds, and / or groups, but do not exclude the presence, occurrence or addition of one or more other features, steps, operations, elements, components, items, kinds, and / or groups. The terms "or", "and / or", "including at least one of the following", etc. used in this application may be interpreted as inclusive, or mean any one or any combination. For example, "including at least one of the following: A, B, C" means "any one of the following: A; B; C; A and B; A and C; B and C; A and B and C", and for another example, "A, B or C" or "A, B and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A and B and C". Exceptions to this definition will only occur when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way.

[0039] It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this document, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, as used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless otherwise indicated in the context.

[0040] It should be understood that the orientations or positional relationships indicated by terms such as "top", "bottom", "up", "down", "vertical", and "horizontal" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description. They do not indicate or imply that the device referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] For ease of description, in the following embodiments, orthogonal spaces determined by horizontal planes and vertical directions are used as examples for illustration, and this premise should not be construed as a limitation to the present application.

[0042] As mentioned above, although the magnetic lens can focus a large beam of ion beam by confining electrons to pull ions, the Lorentz force does not do work and the magnetic lens cannot provide energy to the ions, resulting in poor stability of the ion beam after passing through the magnetic lens. Once momentum exchange occurs with the background gas, it is likely to diverge again.

[0043] In order to solve the problem that the magnetic lens cannot provide energy for ions, an electric lens can be used to focus the large beam current ion beam and increase the ion energy through the electric field. The principle is as follows Figure 1 As shown, the large beam divergent ion beam becomes a parallel beam when passing through the electric lens (aperture D is generally between 100-200mm) 10a, and then passes through the electric field E between the electric lens 10a and the carrier platform 20a. 2 However, due to the presence of a large number of electrons in a large beam divergent ion beam, the ions are disturbed, resulting in insufficient focusing of the ion beam. For example, the diameter of a large beam ion beam with a diameter of 100 mm can only reach 50 mm after focusing. Based on this, the present application provides an ion beam focusing system.

[0044] See also Figure 2 , Figure 2 It is a structural schematic diagram of an ion beam focusing system provided in an embodiment of the present application. The ion beam focusing system may include an electric lens assembly 100, a process chamber 200, a supporting platform 300 and a beam ion source 400.

[0045] The process chamber 200 is grounded to shield the external influence on the internal focusing electric field and control the background vacuum degree when the ion beam focusing system is working. For example, the vacuum degree in the process chamber 200 can be controlled to be 10 -3 ~10Pa to reduce the momentum exchange between the ion beam and the background gas.

[0046] As some examples, the beam ion source 400 can be one or more of a planar cathode, a cylindrical cathode, an annular cathode, a gas ion source, a cathode arc, and the like, and the discharge mode can be one or more of a DC discharge, a pulse discharge, a radio frequency discharge, a medium frequency discharge, a composite pulse discharge, and a high-power pulse discharge.

[0047] Please also see Figure 2 and Figure 3 , Figure 3 1 is a partial structural diagram of an electric lens assembly provided in an embodiment of the present application. The electric lens assembly 100 may include a plurality of micro-element electric lenses 10. All the micro-element electric lenses 10 are spliced ​​to form an electric lens array. The electric lens array is a downward curved surface and is a rotationally symmetrical pattern. Figure 2 The Z axis is the rotational symmetry axis of the electric lens array.

[0048] Specifically, each micro-element electric lens 10 may include an electrode 11 and a hole 12 provided on the electrode 11. The electrode may be made of metal or other conductive materials. All micro-element electric lenses 10 are spliced ​​together to form an electric lens array. The splicing method and specific shape are not particularly limited in the embodiment of the present application, and it is sufficient to ensure that the electric lens array formed by splicing is a rotationally symmetrical figure. Therefore, the electric lens array may be formed by assembling and splicing independent micro-element electric lenses 10, or it may be formed by assembling a plurality of annular parts, each annular part including a plurality of micro-element electric lenses 10; in other embodiments, the electric lens array may also be integrally formed, for example, it may be 3D printed, die-cast, or formed by hot bending and stamping of a sheet material, etc. The electric lens assembly is connected to a first negative pressure V1.

[0049] The carrying platform 300 is used to carry the substrate 500. The electric lens assembly 100 is arranged between the beam ion source 400 and the carrying platform 300. The carrying platform 300 is connected to the second negative voltage V2 to form an electric field with the electric lens assembly 100, and V2<V1<0, that is, the electric potential of the carrying platform 300 is lower than the electric potential of the electric lens assembly 100; the positive ions passing through the electric lens assembly 100 are focused to the central area of ​​the electric lens assembly 100 under the action of the electric field, wherein the central area is a circular area centered on the rotation axis Z and located on the carrying platform 300. The substrate 500 can be arranged in the central area to receive the focused ion beam to achieve micro-machining of the substrate 500. Ideally, the central area can also be the intersection of the rotation axis Z and the carrying platform 300, which is referred to as the focus in this application, and the diameter of the central area can be considered to be 0 at this time. It can be understood that the central area is the target area for focusing, and the diameter of the central area can be adjusted according to the actual application.

[0050] Based on the idea of ​​calculus, this application regards the irregular large beam current ion beam as a large number of uniform micro-element parallel ion beams, and sets a corresponding micro-element electric lens 10 for each micro-element parallel ion beam. Figure 2 and Figure 4 , Figure 4 It is a schematic diagram of the movement of a charged particle provided in an embodiment of the present application, wherein (a) is a schematic diagram of the movement of a charged particle in a sheath fusion state, (b) is a simulation result of the movement of electrons in the sheath, and (c) is a simulation result of the movement of ions in the sheath. When applied, the process chamber 200 can be grounded (the electric potential is 0) to shield the interference of the outside world on the focusing system, and negative pressures V1 and V2 are respectively loaded on the electric lens assembly 100 and the carrier platform 300, and V2<V1<0, so that an electric field is formed between the carrier platform 300 and the electric lens assembly 100. Exemplarily, V1 and V2 can be selected in the range of 0 to -10 kV. The potential of all micro-element electric lenses 10 is V1. When the plasma passes through the hole 12 of the micro-element electric lens 10, the electrons therein are repelled and the positive ions are attracted to pass through, so that a micro-element pure ion beam can be obtained. Since the positive ions passing through the electric lens assembly 100 can be focused to the central area of ​​the electric lens assembly 100 under the action of the electric field, all micro-element pure ion beams are focused to the central area of ​​the electric lens assembly 100. In addition, since the electric lens array is a downward curved surface, the shape can change the initial velocity and force direction of the positive ions when passing through the micro-element electric lens, strengthen the movement of the ions to the central area, and the diameter of the ion beam after focusing can reach less than 10 mm, that is, the diameter of the central area can be less than 10 mm, breaking through the limitations of the original technology. Therefore, the ion focusing system of the present application can eliminate electronic interference, and at the same time, based on the curved surface shape of the electric lens array, strengthen the movement of ions to the center, thereby improving the focusing effect of the ions, that is, a smaller focusing radius can be obtained.

[0051] As some examples, the electric lens array is in the shape of a curved surface that bends downward. For example, the longitudinal cross-section of the electric lens array can be formed by connecting one or more of the curves such as circular arcs, elliptical arcs, hyperbolic segments, parabolic segments, etc., or by connecting at least one of the above curves with a straight line segment. That is, the micro-element electric lens 10 that constitutes the electric lens array can be a spherical surface, an elliptical surface, a hyperbolic surface, a parabola, etc., or at least one of the above curved surfaces can be combined with a plane. "Splicing" is just to more accurately describe the invention idea of ​​the present invention based on "calculus". In specific applications, the electric lens array can adopt an integrated molding solution. It can be understood that the three-dimensional figure of the electric lens array can be obtained by connecting one or more of the above line segments and rotating around one of the ends.

[0052] As some examples, the longitudinal cross section of the electric lens array is arc-shaped, and the curvature of the electric lens array is 0 to 100 m -1 , that is, the electric lens array of this embodiment is a spherical surface. In addition, the diameter of the projection of the electric lens array on a plane perpendicular to the axial direction can be 5 to 200 mm. By controlling the curvature of the arc array and the potential of the carrying platform 300, the micro-element pure ion beams coming out of all the micro-element electric lenses 10 can be focused toward the central area of ​​the electric lens array.

[0053] Preferably, the aperture of the microelement electric lens is greater than 0.001 mm and less than the thickness of the plasma sheath s 0 twice of which,

[0054]

[0055] Where V 0 is the potential of the microelement electric lens, T e is the electron temperature, is the electron Debye length. Among them, ε 0 is the dielectric constant in vacuum, ε 0 =8.854×10 -12 F / m,k B is the Boltzmann constant, k B =1.38×10 -23 J / K, T is the ambient temperature, n e is the plasma density, e is the charge of the electron, e = 1.6 × 10 -19 C.

[0056] As some examples, when PVD technology is used to generate ion beams for surface treatment, the plasma density range is about 10 16 ~10 22 m -3, the electron temperature range is 1 to 10 eV. According to the above formula, it can be determined that the aperture of the micro-element electric lens 10 can be 0.001 to 10 mm. 10 mm can ensure that the aperture of the micro-element electric lens is smaller than the thickness s of the plasma sheath. 0 The aperture is twice as large as that of the microelement electric lens 10. In addition, the aperture is too small to be processed. Preferably, the aperture range can be 0.05 to 5 mm, and more preferably, the aperture range can be 0.1 to 1 mm. In addition, the aperture spacing between two adjacent microelement electric lenses 10 can be 0.001 to 10 mm.

[0057] As some examples, the distance between the electric lens assembly 100 of the ion beam focusing system and the beam ion source 400 is 10 to 300 mm. If the distance is too small, the electric lens assembly 100 will interfere with the beam ion source 400. If the distance is too large, it will cause a large loss of positive ions.

[0058] As some examples, the distance between the lower end of the electric lens assembly 100 and the supporting platform 300 can be 10 to 300 mm. If the distance is too small, the movement time of the ions is too short and there is no time to focus, resulting in poor focusing effect; if the distance is too large, it will cause a large loss of positive ions.

[0059] See also Figure 5 , Figure 5 : This is a simulation diagram of the process effect of the ion beam focusing system provided by the embodiment of the present application, wherein (a) is the ion density distribution diagram; (b) is the deposition flux curve of ions on the substrate (r = 0mm is the rotational symmetry axis Z). For the parameters of the electric lens assembly used in the simulation, please refer to Figure 6 , Figure 6 1 is a schematic diagram of an electric lens assembly provided by an embodiment of the present application, wherein (a) is a bottom view, (b) is a cross-sectional view along line AA in (a), and (c) is a partial view. Specifically, the simulation conditions and parameters are as follows: the electric lens assembly 100 is a spherical surface with a thickness of 0.5 mm, the diameter of the projection circle of the electric lens assembly 100 on a plane perpendicular to the rotation axis is 140 mm, the diameter of the hole on the electric lens assembly 100 is 0.3 mm, the center distance between two adjacent holes is 0.6 mm, and the focal length (the distance between the center area and the center of the top surface of the electric lens assembly 100) is 80 mm; a negative pressure of -100 V is loaded on the electric lens assembly 100, a negative pressure of -1500 V is loaded on the supporting platform 300, and the plasma density is 10 -18 m -3 The distance between the beam ion source 400 and the electric lens assembly 100 is 60 mm, and the distance between the electric lens assembly 100 and the carrying platform 300 is 80 mm.

[0060] Depend on Figure 5It can be seen that the ion density is uniformly distributed when just passing through the electric lens array. Under the action of the focusing electric field between the electric lens assembly 100 and the carrier platform 300, the ions are continuously focused toward the central axis Z during the movement. Finally, the ions present an extremely high deposition flux at the focal point (r=0 mm) on the substrate. As the distance to the focal point increases, the ion deposition flux decreases rapidly, thereby achieving a high degree of focusing of the positive ions in the large ion beam. The ion beam diameter can be focused from 140 mm to less than 4 mm.

[0061] In one embodiment, see Figure 7 , Figure 7 It is a structural schematic diagram of another ion beam focusing system provided in an embodiment of the present application, wherein at least two electric lens assemblies 100 are provided and are arranged in sequence from the beam ion source 400 to the supporting platform 300 to form multi-stage focusing. Figure 7 In the example of setting two electric lens assemblies 100A and 100B to form two-stage focusing, the electric lens assembly 100A initially focuses all micro-element ion beams onto the electric lens assembly 100B, and the electric lens assembly 100B enhances the focusing of the micro-element ion beams by increasing the curvature, and further focuses them onto the substrate 500. The two-stage focusing can gradually focus the ion beam, which can be applied to ion beams with larger areas.

[0062] Exemplarily, the distance between the carrying platform 300 and the lower end of the electric lens array can be 10 to 1000 mm. The size of the carrying platform 300 is smaller than the diameter of the projection of the electric lens array on the plane perpendicular to the axial direction (rotational symmetry axis Z). For example, the diameter of the carrying platform 300 can be 1 to 1000 mm.

[0063] As an example, the carrier platform 300 may be a flat plate structure, a porous structure or a hollow grid structure, and the interior of the carrier platform 300 is an equipotential region. The substrate 500 may be placed on the surface of the carrier platform 300 (eg Figure 2 ), or it can be placed in the equipotential area inside the carrying platform 300 (as shown in Figure 8 ). The diameter of the focused ion beam can be adjusted by controlling the potential of the carrier platform 300, for example, the diameter of the focused ion beam can be increased, and the whole ion beam can be formed into a parallel beam and deposited on the substrate 500. The substrate 500 can be a plane, arc, trapezoid, or any other structure with protrusions or grooves. For example, the surface of the substrate 500 can be provided with a groove, and the groove is located at the focus of the electric lens array.

[0064] In one embodiment, see Figure 8 , Figure 8It is a structural schematic diagram of another ion beam focusing system provided in an embodiment of the present application. The ion beam focusing system may also include a magnetic lens 600 disposed in the process chamber 200. The magnetic lens 600 is disposed around the outer side of the supporting platform 300 and the electric lens assembly 100. The magnetic lens can further enhance the ion beam focusing.

[0065] Preferably, the magnetic field strength of the magnetic lens 600 gradually increases from top to bottom, that is, the magnetic field gradually increases along the ion beam output direction, and the magnetic field strength is greater near the carrier platform 300, which can improve the accuracy of ion beam focusing. As an example, the magnetic field of the magnetic lens 600 can be generated by a coil, and the coil winding density increases from sparse to dense from top to bottom.

[0066] In some embodiments, the ion beam focusing system of the present application can be used to achieve functions such as sample cleaning, coating deposition, enhanced discharge, and material direct writing.

[0067] The above is a detailed introduction to an ion beam focusing system provided by the present application. This article uses specific examples to illustrate the principles and implementation methods of the present application. It should be noted that in the present application, the descriptions of each embodiment have their own emphasis. For parts that are not described or recorded in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0068] The above are only preferred embodiments of the present application, and the patent scope of the present application is not limited thereto. The various technical features of the technical solution of the present application can be arbitrarily combined. In order to make the description concise, not all possible combinations of the various technical features in the above embodiments are described. Any equivalent structure or equivalent process transformation made using the contents of the specification and drawings of this application, or directly or indirectly used in other related technical fields, as long as there is no contradiction in the combination of these technical features, are equally included in the patent protection scope of the present application.

Claims

1. An ion beam focusing system, characterized in that: It comprises a process chamber, and a beam ion source, an electric lens assembly and a carrying platform which are sequentially arranged from top to bottom in the process chamber; The process chamber is grounded; The electric lens assembly includes a plurality of micro-element electric lenses, and the plurality of micro-element electric lenses are spliced ​​to form an electric lens array; The electric lens array is a downward curved surface and a rotationally symmetrical pattern; The electric lens assembly is connected to a first negative pressure V1; The carrying platform is connected to a second negative voltage V2 to form an electric field with the electric lens assembly, and V2<V1<0; After the plasma generated by the beam ion source passes through the electric lens assembly, the positive ions therein are focused toward the central area of ​​the electric lens assembly under the action of the electric field. The central area is a circular area centered on the rotation axis and located on the supporting platform.

2. The ion beam focusing system according to claim 1, characterized in that: The longitudinal cross section of the electric lens array is formed by connecting one or more of circular arcs, elliptical arcs, hyperbolic segments, and parabolic segments; or, The longitudinal cross section of the electric lens array is formed by connecting one or more of a circular arc, an elliptical arc, a hyperbola segment, and a parabola segment with a straight line segment.

3. The ion beam focusing system according to claim 2, characterized in that: The longitudinal cross section of the electric lens array is in the shape of an arc; and, The curvature of the electric lens array is 0 to 100 m -1 ; and / or, the diameter of the projection of the electric lens array on a plane perpendicular to the axial direction is 5 to 200 mm.

4. The ion beam focusing system according to claim 1, characterized in that: The aperture of the microelement electric lens is greater than or equal to 0.001 mm and less than or equal to twice the thickness s0 of the plasma sheath, wherein: Where V0 is the potential of the microelement electric lens, T e is the electron temperature, is the electron Debye length.

5. The ion beam focusing system according to claim 4, characterized in that: The aperture of the micro-element electric lens is 0.001-10 mm; and / or, The hole spacing between two adjacent micro-element electric lenses is 0.001-10 mm.

6. The ion beam focusing system according to claim 1, characterized in that: The distance between the electric lens assembly and the beam ion source is 10 to 300 mm; and / or, The distance between the lower end of the electric lens assembly and the carrying platform is 10 to 300 mm.

7. The ion beam focusing system according to claim 1, characterized in that: At least two electric lens assemblies are provided and are arranged in sequence from the ion source to the carrying platform to form multi-stage focusing.

8. The ion beam focusing system according to any one of claims 1 to 7, characterized in that: Also included is a magnetic lens disposed in the process chamber; The magnetic lens is arranged around the outer side of the carrying platform and the electric lens assembly.

9. The ion beam focusing system according to claim 8, characterized in that: The magnetic field strength of the magnetic lens gradually increases from top to bottom.

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