Electrostatic deflector for focusing ion beam and assembly process thereof

Abstract

The invention relates to the technical field of charged particle beam control, and discloses an electrostatic deflector for a focused ion beam and an assembly process thereof, the electrostatic deflector comprises an electrode assembly, a mounting flange, an insulation structure and a positioning structure; an upper electrode and a lower electrode of the electrode assembly are correspondingly arranged; part of the upper electrode is embedded into the mounting flange; the insulating structure is arranged on one side, far away from the upper electrode, of the mounting flange, and part of the lower electrode is embedded into the insulating structure; the positioning structure sleeves the lower electrode; the thermal expansion coefficient of the electrode assembly is A, the thermal expansion coefficient of the insulation structure is B, and 1 < = A / B < = 1.5. The proportional relation between the thermal expansion coefficients of the electrode assembly and the insulation structure is limited, the thermal expansion coefficients of the electrode assembly and the insulation structure are matched, the deformation quantity difference of the electrode assembly and the insulation structure under the extreme working condition is reduced, thermal stress cracking is avoided, and the assembly precision and structural integrity of the electrode assembly and the insulation structure are maintained; the electric field is distributed according to design, and distortion is avoided.

Description

Technical Field

[0001] This invention relates to the field of charged particle beam manipulation technology, specifically to an electrostatic deflector for focusing ion beams and its assembly process. Background Technology

[0002] Electrostatic deflectors are key components in high-end equipment such as particle accelerators, electron microscopes, and mass spectrometers. They are mainly used to control the direction, shape, and quality of charged particle beams (such as electrons and ions). Among them, multipole deflectors are valued for their ability to generate higher-order electric field distributions to correct nonlinear aberrations of the particle beam and achieve precise control of the particle beam.

[0003] However, in existing electrostatic deflectors, under extreme conditions, the difference in deformation between the electrodes and the insulating ceramic increases, leading to thermal stress concentration and causing problems such as ceramic cracking and electric field distortion. Summary of the Invention

[0004] This invention provides an electrostatic deflector for focused ion beams and its assembly process to solve the problems of ceramic cracking and electric field distortion caused by the large difference in deformation between the electrode and the insulating ceramic.

[0005] In a first aspect, the present invention provides an electrostatic deflector for a focused ion beam, comprising an electrode assembly, a mounting flange, an insulating structure, and a positioning structure; the electrode assembly includes an upper electrode and a lower electrode, the upper electrode and the lower electrode being correspondingly disposed; the mounting flange has a mounting hole, and a portion of the upper electrode is embedded in the mounting hole; the insulating structure is disposed on the side of the mounting flange away from the upper electrode and is connected to the mounting flange, and a portion of the lower electrode is embedded within the insulating structure; the positioning structure is sleeved on the lower electrode and disposed near the end of the lower electrode away from the insulating structure; the coefficient of thermal expansion of the electrode assembly is A, and the coefficient of thermal expansion of the insulating structure is B, satisfying 1≤A / B≤1.5.

[0006] Beneficial effects: By limiting the proportional relationship between the thermal expansion coefficients of the electrode assembly and the insulation structure, the thermal expansion coefficients of the electrode assembly and the insulation structure are matched, reducing the deformation difference between the electrode assembly and the insulation structure under extreme working conditions. The thermal stress generated by the mutual constraint between the two is far below the material's tolerance limit, avoiding thermal stress cracking. The small deformation difference can maintain the assembly accuracy and structural integrity of the electrode assembly and the insulation structure, ensuring that the electric field is distributed according to the design and avoiding distortion.

[0007] In one optional embodiment, the difference between the coefficient of thermal expansion A of the electrode assembly and the coefficient of thermal expansion B of the insulation structure is less than or equal to 0.6 × 10⁻⁶. -6 / ℃.

[0008] Beneficial effects: By further limiting the thermal expansion coefficients of the electrode assembly and the insulation structure, the deformation of the electrode assembly and the insulation structure under extreme temperature conditions can be precisely matched. Even under severe temperature changes, the difference in the expansion and contraction amplitude between the two is controlled within a very small range. This not only completely avoids the risk of thermal stress cracking, but also maximizes the relative positional accuracy of the electrode and the ceramic, ensuring the stability and consistency of the electric field distribution and meeting the stringent requirements of high-precision ion beam manipulation for electric field uniformity.

[0009] In one alternative embodiment, the electrode assembly is made of Kova iron-nickel-cobalt alloy, and the insulating structure is made of zirconia-toughened alumina ceramic.

[0010] In one optional embodiment, the upper electrode is divided to form a plurality of first electrode units, and the lower electrode is divided to form a plurality of second electrode units, wherein the plurality of second electrode units are configured in a one-to-one correspondence with the plurality of first electrode units.

[0011] Beneficial effects: The upper and lower electrodes are processed as a single integrated unit, and then divided to form multiple first electrode units and multiple second electrode units, which reduces dimensional errors and improves the dimensional consistency of the first electrode units and the second electrode units.

[0012] In one alternative embodiment, the electrode assembly further includes a first coating and a second coating, the first coating being applied to the upper electrode and the lower electrode, and the second coating being applied to the first coating, wherein the dielectric constant of the first coating is higher than that of the second coating.

[0013] Beneficial Effects: By designing a gradient dielectric constant through a dual-layer coating, a composite structure is formed, consisting of a high-dielectric inner layer and a low-dielectric outer layer. The first coating, with its high dielectric properties, enhances the electric field carrying capacity of the electrode surface, reduces electric field leakage, and improves the response speed of ion beam deflection control. The second coating, with its low dielectric properties, reduces charge accumulation on the electrode surface, preventing electric field distortion caused by charge adsorption. Simultaneously, it improves the coating's wear resistance and anti-fouling properties, extending the service life of the electrode assembly. The synergistic effect of the dual coatings ensures both the precision of electric field control and optimizes the reliability of the electrodes.

[0014] In one alternative embodiment, the lower electrode has a first slot, a portion of the insulating structure is embedded in the first slot and is interference-fitted with the lower electrode, the interference being 0.005 mm to 0.01 mm.

[0015] Beneficial effects: Through precise control of the interference fit design, the insulation structure and the first slot of the lower electrode form a tight fit connection structure, which can not only ensure the firmness of the connection and avoid relative displacement under extreme working conditions, but also prevent the insulation structure from cracking due to assembly stress caused by excessive interference. On the other hand, the tight interference fit reduces the gap between the two, reduces the risk of discharge gap in vacuum environment, and improves the overall rigidity of the structure, further ensuring the stability of electric field distribution.

[0016] In one alternative embodiment, the insulating structure includes a plurality of protrusions and a plurality of recesses, wherein the plurality of protrusions and recesses are sequentially and alternately connected along the axial direction to form a concave-convex structure.

[0017] Beneficial effects: The concave-convex structure can suppress the local concentration of electric field on the ceramic surface, avoid electric field distortion, and at the same time improve the insulation and withstand voltage performance of the ceramic, making it suitable for high-voltage and high-precision ion beam manipulation scenarios.

[0018] Secondly, the present invention also provides an assembly process for an electrostatic deflector, used for assembling the aforementioned electrostatic deflector, comprising the following steps: S1. Use assembly fixtures to position the upper electrode, the lower electrode, and the insulating structure. S2. Assemble the electrode assembly, the mounting flange, the insulation structure, and the positioning structure using the assembly fixture; S3. After assembly, observe the roundness of the center hole of the upper electrode under a microscope and calibrate it with a ruler. Use a laser interferometer to measure the runout of the end face of the upper electrode away from the lower electrode. If the deviation is large, adjust the upper electrode. S4. Place the electrostatic deflector in a vacuum environment and let it stand. Then, use the method in step S3 to test the roundness change. If it passes the test, fix it with vacuum-resistant high-temperature adhesive.

[0019] Beneficial effects: The above assembly process achieves high-precision assembly of the electrostatic deflector; the roundness of the upper electrode is detected by dual detection using a microscope and a laser interferometer to ensure the accuracy of the core working parts; the vacuum static test simulates the actual working environment, which can eliminate the risk of structural deformation under vacuum conditions; and the assembly structure is fixed by vacuum-resistant high-temperature adhesive to ensure its stability under extreme working conditions.

[0020] In one optional embodiment, the upper electrode is divided into multiple first electrode units, each of which is provided with a set screw thread hole. In step S3, the method for adjusting the upper electrode includes: The roundness of the center hole of the upper electrode is corrected by adjusting the set screw thread hole of the first electrode unit with large deviation using tools.

[0021] Beneficial effects: By directly applying the tool to the first electrode unit with large deviations, micron-level fine-tuning can be achieved. Compared with overall disassembly and adjustment, the operation is more efficient and will not affect other assembled components. The adjustment process can be combined with real-time microscope inspection to ensure that the roundness of the central hole quickly meets the design requirements, guarantee the regularity of the ion beam channel, and avoid problems such as ion beam divergence and reduced deflection accuracy caused by channel shape deviation.

[0022] In one optional embodiment, the coefficient of thermal expansion of the assembly tooling is less than or equal to 1 × 10⁻⁶. -6 / ℃.

[0023] Beneficial effects: By limiting the thermal expansion coefficient of the assembly tooling, the positioning accuracy is avoided from being affected by the temperature change of the tooling itself, thus providing a reliable tooling guarantee for high-precision assembly. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the overall structure of the electrostatic deflector according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall structure of the upper electrode according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the overall structure of the lower electrode according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the overall structure of the insulation structure according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the overall structure of the assembly tooling according to an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures: 10. Electrode assembly; 11. Upper electrode; 111. First electrode unit; 1111. Set screw threaded hole; 12. Lower electrode; 121. Second electrode unit; 122. First slot; 123. Second slot; 20. Mounting flange; 30. Insulation structure; 31. Protrusion; 32. Recess; 40. Positioning structure; 50. Assembly fixture; 51. Positioning bracket; 52. Positioning flange. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The following is combined Figures 1 to 5 The following describes embodiments of the present invention.

[0029] According to an embodiment of the present invention, in a first aspect, an electrostatic deflector for focusing an ion beam is provided, comprising an electrode assembly 10, a mounting flange 20, an insulating structure 30, and a positioning structure 40; the electrode assembly 10 includes an upper electrode 11 and a lower electrode 12, the upper electrode 11 and the lower electrode 12 being correspondingly disposed; the mounting flange 20 has a mounting hole, and a portion of the upper electrode 11 is embedded in the mounting hole; the insulating structure 30 is disposed on the side of the mounting flange 20 away from the upper electrode 11 and is connected to the mounting flange 20, and a portion of the lower electrode 12 is embedded in the insulating structure 30; the positioning structure 40 is sleeved on the lower electrode 12 and disposed near the end of the lower electrode 12 away from the insulating structure 30; the coefficient of thermal expansion of the electrode assembly 10 is A, and the coefficient of thermal expansion of the insulating structure 30 is B, satisfying 1≤A / B≤1.5.

[0030] By applying the electrostatic deflector of this embodiment, the thermal expansion coefficients of the electrode assembly 10 and the insulation structure 30 are matched by limiting the proportional relationship between them. This reduces the difference in deformation between the electrode assembly 10 and the insulation structure 30 under extreme working conditions. The thermal stress generated by the mutual constraint between the two is far below the material's tolerance limit, thus avoiding thermal stress cracking. The small difference in deformation can maintain the assembly accuracy and structural integrity of the electrode assembly 10 and the insulation structure 30, ensuring that the electric field is distributed according to the design and avoiding distortion.

[0031] Specifically, in this embodiment, the insulating structure 30 is an insulating ceramic, and the positioning structure 40 is a positioning ceramic.

[0032] Furthermore, the difference between the coefficient of thermal expansion A of the electrode assembly 10 and the coefficient of thermal expansion B of the insulation structure 30 is less than or equal to 0.6 × 10⁻⁶. -6 / ℃.

[0033] It is worth noting that by further limiting the coefficients of thermal expansion of the electrode assembly 10 and the insulating structure 30, the deformation of the electrode assembly 10 and the insulating structure 30 under extreme temperature conditions is precisely matched. Even when faced with drastic temperature changes, the difference in the expansion and contraction range between the two is controlled within a very small range. This not only completely avoids the risk of thermal stress cracking, but also maximizes the relative positional accuracy of the electrode and the ceramic, ensuring the stability and consistency of the electric field distribution and meeting the stringent requirements of high-precision ion beam manipulation for electric field uniformity.

[0034] Specifically, in this embodiment, the electrode assembly 10 is made of Kova iron-nickel-cobalt alloy, with a coefficient of thermal expansion A of 4.8 × 10⁻⁶. -6 / ℃ to 5.0×10 -6 / ℃, the insulation structure 30 is made of zirconia-toughened alumina ceramic, with a coefficient of thermal expansion B of 5.2×10. -6 / ℃ to 5.4×10 -6 / ℃.

[0035] In one embodiment, the upper electrode 11 is divided to form a plurality of first electrode units 111, and the lower electrode 12 is divided to form a plurality of second electrode units 121, with the plurality of second electrode units 121 corresponding to the plurality of first electrode units 111.

[0036] Specifically, such as Figure 2 and Figure 3 As shown, the upper electrode 11 is divided into eight first electrode units 111, and the lower electrode 12 is divided into eight second electrode units 121 to form an octet electrostatic deflector.

[0037] It should be noted that in other alternative embodiments, the number of the first electrode unit 111 and the second electrode unit 121 can be adjusted according to actual needs.

[0038] It is worth noting that the upper electrode 11 and the lower electrode 12 are processed as a whole and then divided into multiple first electrode units 111 and multiple second electrode units 121 to reduce size error and improve the size consistency of the first electrode units 111 and the second electrode units 121. The octet electrostatic deflector can generate a higher-order electric field to effectively compensate for complex aberrations such as third-order spherical aberration, coma, and astigmatism, and realize atomic-level observation.

[0039] Specifically, the octet electrostatic deflector consists of eight symmetrically arranged first electrode units 111 and second electrode units 121. Positive and negative voltages are alternately applied to the electrodes to form an octet electrostatic field. Its electric field distribution satisfies Laplace's equation (…). With Φ=0, the potential distribution can be approximated by a higher-order expansion in polar coordinates: Φ(r,θ)=Φ0r4cos(4θ); Where: r is the radial distance, θ is the azimuth angle; Φ0 is a constant related to the electrode voltage; cos(4θ) reflects the octet symmetry.

[0040] In one embodiment, the electrode assembly 10 further includes a first coating and a second coating, the first coating being applied to the upper electrode 11 and the lower electrode 12, and the second coating being applied to the first coating, wherein the dielectric constant of the first coating is higher than that of the second coating.

[0041] Specifically, in this embodiment, the first coating is an Al2O3-TiO2 composite layer, and the second coating is a SiO2 layer.

[0042] It should be noted that in related technologies, a single gradient coating is often used, resulting in a slow response speed of the electrode assembly 10 and significant electric field leakage.

[0043] It is worth noting that through the gradient dielectric constant design of the dual-layer coating, a composite structure of "high dielectric inner layer to low dielectric outer layer" is formed. The first coating, with its high dielectric properties, enhances the electric field carrying capacity of the electrode surface, reduces electric field leakage, and improves the response speed of ion beam deflection control. The second coating, with its low dielectric properties, reduces charge accumulation on the electrode surface, avoids electric field distortion caused by charge adsorption, and simultaneously improves the wear resistance and anti-fouling performance of the coating, extending the service life of the electrode assembly 10. The synergistic effect of the dual coatings ensures both the precision of electric field control and optimizes the reliability of the electrode.

[0044] In one embodiment, the lower electrode 12 has a first slot 122, and a partial insulating structure 30 is embedded in the first slot 122 and is interference-fitted with the lower electrode 12, with an interference amount of 0.005 mm to 0.01 mm.

[0045] It should be noted that the insulating structure 30 is interference-fitted with the lower electrode 12 through the first slot 122. If the interference is too small, the connection between the insulating structure 30 and the lower electrode 12 will be weak, resulting in relative displacement and causing the electrostatic deflector to become loose. If the interference is too large, the insulating structure 30 may crack due to excessive stress during assembly.

[0046] It is worth noting that the interference fit design with precise control of the interference amount enables the insulation structure 30 and the first slot 122 of the lower electrode 12 to form a tightly fitting connection structure. This ensures the firmness of the connection and avoids relative displacement under extreme working conditions, while also preventing the insulation structure 30 from cracking due to assembly stress caused by excessive interference. On the other hand, the tight interference fit reduces the gap between the two, lowers the risk of discharge gap in a vacuum environment, and improves the overall rigidity of the structure, further ensuring the stability of the electric field distribution.

[0047] In one embodiment, the lower electrode 12 also has a second slot 123, and a partial positioning structure 40 is embedded in the second slot 123.

[0048] In one embodiment, such as Figure 4 As shown, the insulating structure 30 includes a plurality of protrusions 31 and a plurality of recesses 32, which are alternately connected in sequence along the axial direction to form a concave-convex structure.

[0049] It should be noted that the electrostatic deflector used for focused ion beams needs to withstand high voltages of 10kV to 30kV. In related technologies, the problem of concentrated electric field at the electrode edge and insufficient creepage distance at the insulation interface are combined, making the insulation structure 30 easily broken down.

[0050] It is worth noting that the creepage distance of the concave-convex structure is an improvement over related technologies, which can suppress the local concentration of electric field on the ceramic surface, avoid electric field distortion, and improve the insulation and withstand voltage performance of the ceramic, making it suitable for high-voltage and high-precision ion beam manipulation scenarios.

[0051] In this example, the operation of the octet electrostatic deflector is as follows: eight sets of first electrode units 111 and second electrode units 121 are evenly distributed in the circumferential direction with the central axis as the axis of symmetry, and adjacent electrodes have opposite polarities, forming a periodic electrostatic field; a charged particle beam is incident near the central axis, and the initial trajectory is assumed to be an ideal straight line; if the particle deviates from the center, it will enter the high field strength region and be subjected to a nonlinear force (F∝r3) proportional to the displacement r3, causing its trajectory to be strongly deflected; by adjusting the electrode voltage, the intensity of the nonlinear effect can be controlled, thereby compressing the lateral distribution of the beam (suppressing edge particle diffusion) and correcting higher-order optical aberrations.

[0052] According to an embodiment of the present invention, in a second aspect, an assembly process for an electrostatic deflector is also provided for assembling the aforementioned electrostatic deflector, comprising the steps of: S1. Use assembly fixture 50 to position the upper electrode 11, lower electrode 12 and insulating structure 30. S2. Assemble the electrode assembly 10, mounting flange 20, insulation structure 30 and positioning structure 40 using assembly fixture 50. S3. After assembly, observe the roundness of the center hole of the upper electrode 11 under a microscope and calibrate it with a ruler. Use a laser interferometer to measure the runout of the end face of the upper electrode 11 away from the lower electrode 12. If the deviation is large, adjust the upper electrode 11. S4. Place the electrostatic deflector in a vacuum environment and let it stand. Then, use the method in step S3 to test the roundness change. If it passes the test, fix it with vacuum-resistant high-temperature adhesive.

[0053] It is worth noting that the above assembly process achieves high-precision assembly of the electrostatic deflector; the roundness of the upper electrode 11 is detected by dual detection using a microscope and a laser interferometer to ensure the accuracy of the core working parts; the actual working environment is simulated by vacuum static testing, which can eliminate the risk of structural deformation under vacuum conditions; and the assembly structure is fixed by vacuum-resistant high-temperature adhesive to ensure its stability under extreme working conditions.

[0054] Specifically, such as Figure 5 As shown, the assembly fixture 50 includes a positioning bracket 51 and a positioning flange 52. There are two positioning flanges 52, which are connected to the positioning bracket 51. The two positioning flanges 52 are respectively positioned to correspond to the upper electrode 11 and the lower electrode 12.

[0055] Specifically, in step S4, the electrostatic deflector is placed in a 1×10 -5 The sample was placed in a vacuum environment and the change in the roundness of the central hole was detected.

[0056] In one embodiment, such as Figure 2 As shown, the upper electrode 11 is divided into multiple first electrode units 111, and each first electrode unit 111 is provided with a set screw thread hole 1111. In step S3, the method for adjusting the upper electrode 11 includes: The roundness of the center hole of the upper electrode 11 is corrected by adjusting the set screw thread hole 1111 of the first electrode unit 111 with large deviation using a tool.

[0057] It is worth noting that by directly applying the tool to the first electrode unit 111 with large deviations, micron-level fine-tuning can be achieved. Compared with overall disassembly and adjustment, the operation is more efficient and will not affect other assembled components. The adjustment process can be combined with real-time microscope inspection to ensure that the roundness of the central hole quickly meets the design requirements, guarantee the regularity of the ion beam channel, and avoid problems such as ion beam divergence and reduced deflection accuracy caused by channel shape deviation.

[0058] In one embodiment, the coefficient of thermal expansion of the assembly tooling 50 is less than or equal to 1 × 10⁻⁶. -6 / ℃.

[0059] It should be noted that if the coefficient of thermal expansion of the assembly fixture 50 is too large, the assembly fixture 50 will undergo large deformation under the conditions of high plasma beam energy and high beam current density, thereby affecting the assembly positioning accuracy of the electrostatic deflector.

[0060] It is worth noting that by limiting the thermal expansion coefficient of the assembly tooling to 50, the positioning accuracy is avoided from being affected by the temperature change of the tooling itself, thus providing a reliable tooling guarantee for high-precision assembly.

[0061] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An electrostatic deflector for focusing an ion beam, characterized in that, include: An electrode assembly (10) includes an upper electrode (11) and a lower electrode (12), wherein the upper electrode (11) and the lower electrode (12) are respectively disposed. Mounting flange (20), the mounting flange (20) has mounting holes, and part of the upper electrode (11) is embedded in the mounting holes; An insulating structure (30) is disposed on the side of the mounting flange (20) away from the upper electrode (11) and connected to the mounting flange (20), and a portion of the lower electrode (12) is embedded in the insulating structure (30); A positioning structure (40) is sleeved on the lower electrode (12) and disposed near the end of the lower electrode (12) away from the insulating structure (30); The coefficient of thermal expansion of the electrode assembly (10) is A, and the coefficient of thermal expansion of the insulation structure (30) is B, satisfying 1≤A / B≤1.

5.

2. The electrostatic deflector for focusing an ion beam according to claim 1, characterized in that, The difference between the coefficient of thermal expansion A of the electrode assembly (10) and the coefficient of thermal expansion B of the insulating structure (30) is less than or equal to 0.6 × 10⁻⁶. -6 / ℃.

3. The electrostatic deflector for focusing an ion beam according to claim 2, characterized in that, The electrode assembly (10) is made of Kova iron-nickel-cobalt alloy, and the insulating structure (30) is made of zirconia toughened alumina ceramic.

4. The electrostatic deflector for focusing an ion beam according to any one of claims 1-3, characterized in that, The upper electrode (11) is divided to form a plurality of first electrode units (111), and the lower electrode (12) is divided to form a plurality of second electrode units (121). The plurality of second electrode units (121) are arranged in a one-to-one correspondence with the plurality of first electrode units (111).

5. The electrostatic deflector for focusing an ion beam according to any one of claims 1-3, characterized in that, The electrode assembly (10) further includes a first coating and a second coating. The first coating is applied to the upper electrode (11) and the lower electrode (12), and the second coating is applied to the first coating. The dielectric constant of the first coating is higher than that of the second coating.

6. The electrostatic deflector for focusing an ion beam according to any one of claims 1-3, characterized in that, The lower electrode (12) has a first slot (122), and part of the insulating structure (30) is embedded in the first slot (122) and is interference-fitted with the lower electrode (12) with an interference amount of 0.005 mm to 0.01 mm.

7. The electrostatic deflector for focusing an ion beam according to any one of claims 1-3, characterized in that, The insulating structure (30) includes a plurality of protrusions (31) and a plurality of recesses (32), which are sequentially and alternately connected along the axial direction to form a concave-convex structure.

8. An assembly process for an electrostatic deflector, used for assembling the electrostatic deflector according to any one of claims 1 to 7, characterized in that, Including the following steps: S1. The upper electrode (11), the lower electrode (12) and the insulating structure (30) are positioned using the assembly fixture (50); S2. The electrode assembly (10), the mounting flange (20), the insulation structure (30) and the positioning structure (40) are assembled using the assembly fixture (50); S3. After assembly, observe the roundness of the center hole of the upper electrode (11) under a microscope and calibrate it with a ruler. Use a laser interferometer to measure the runout of the end face of the upper electrode (11) away from the lower electrode (12). If the deviation is large, adjust the upper electrode (11). S4. Place the electrostatic deflector in a vacuum environment and let it stand. Then, use the method in step S3 to test the roundness change. If it passes the test, fix it with vacuum-resistant adhesive.

9. The assembly process of the electrostatic deflector according to claim 8, characterized in that, The upper electrode (11) is divided into multiple first electrode units (111), each of which is provided with a set screw thread hole (1111). In step S3, the method for adjusting the upper electrode (11) includes: The roundness of the center hole of the upper electrode (11) is corrected by adjusting the set screw thread hole (1111) of the first electrode unit (111) with large deviation by using a tool.

10. The assembly process of the electrostatic deflector according to claim 8, characterized in that, The coefficient of thermal expansion of the assembly tooling (50) is less than or equal to 1×10⁻⁶. -6 / ℃.

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