Argon ion beam scanning electron microscope, ion optical lens barrel and magnetic shielding device

Abstract

The invention provides an ion source magnetic shielding device for an argon ion beam scanning electron microscope, the magnetic shielding device comprises multiple layers of magnetic shielding structures and multiple isolation elements, the multiple layers of magnetic shielding structures are spaced and coaxial through the isolation elements, and the multiple layers of magnetic shielding structures are installed on the outer side of an ion source to isolate a magnetic field generated by an ion source permanent magnet. And interference on electron beam imaging is prevented. The device can effectively isolate a magnetic field generated by a permanent magnet of an electron cyclotron resonance (ECR) ion source, prevents the ECR ion source from interfering with electron beam imaging, ensures the imaging performance of equipment, is simple and compact in structure, low in cost, easy to install and maintain and excellent in magnetic shielding performance, realizes an extremely low magnetic field level, and is suitable for large-scale popularization and application. The magnetic field intensity is lower than 50nT, and the method has a good application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of argon ion beam scanning electron microscopes, in particular to an argon ion beam scanning electron microscope, an ion optical lens barrel and a magnetic shielding device. Background Art

[0002] The argon ion beam scanning electron microscope is a dual-beam electron microscope platform that integrates an argon ion gun on a field emission scanning electron microscope. The system achieves high-quality sample surface analysis by in-situ polishing and high-resolution scanning imaging of the observed sample in the scanning electron microscope sample chamber. The ion gun uses an electron cyclotron resonance ion source, which uses the phenomenon of electron cyclotron resonance in a high-frequency electromagnetic field to generate ions through collisions between electrons and atoms or molecules in the gas, providing a high-energy and large-beam ion beam. However, since the ion source uses permanent magnets to generate a strong magnetic field to make the electrons cyclotron, the magnetic field will interfere with the electron beam imaging, resulting in a decrease in imaging quality. Therefore, a magnetic shielding device is needed to shield the permanent magnet of the electron cyclotron resonance ion source to reduce interference with electron beam imaging. Summary of the invention

[0003] In order to achieve the above-mentioned objectives and other advantages of the present invention, the first objective of the present invention is to provide an ion source magnetic shielding device for an argon ion beam scanning electron microscope, comprising a multi-layer magnetic shielding structure and a plurality of isolation elements. The multi-layer magnetic shielding structures are spaced and coaxial by isolation elements. The multi-layer magnetic shielding structure is installed on the outside of the ion source to isolate the magnetic field generated by the permanent magnet of the ion source to prevent interference with electron beam imaging.

[0004] Furthermore, the magnetic shielding structure is made of a metal material with high magnetic permeability.

[0005] Furthermore, the multi-layer magnetic shielding structure is configured as two coaxial magnetic shielding cylinders, the innermost magnetic shielding cylinder is installed outside the ion source, and the outermost magnetic shielding cylinder is installed outside the innermost magnetic shielding cylinder.

[0006] Furthermore, the multi-layer magnetic shielding structure is configured as three magnetic shielding tubes, the innermost magnetic shielding tube is installed outside the ion source, the middle magnetic shielding tube is installed outside the innermost magnetic shielding tube, and the outermost magnetic shielding tube is installed outside the middle magnetic shielding tube.

[0007] Furthermore, the distance between the multi-layer magnetic shielding structure and the permanent magnet of the ECR ion source is 2 mm-15 mm.

[0008] Furthermore, the thickness of the magnetic shielding sleeve is 0.5 mm-2 mm.

[0009] Furthermore, a through hole is provided on the magnetic shielding cylinder, and the diameter of the through hole is 1 mm-6 mm.

[0010] Furthermore, the positions of the through holes on the adjacent magnetic shielding cylinders are not interconnected.

[0011] Furthermore, the outermost magnetic shielding tube is made of high magnetic permeability material, and the innermost magnetic shielding tube is made of high magnetic permeability material.

[0012] Furthermore, the outermost magnetic shielding tube adopts a high magnetic permeability soft magnet, the middle magnetic shielding tube adopts a high magnetic permeability material, and the innermost magnetic shielding tube adopts a high magnetic permeability material.

[0013] Further, the isolation element is configured as an isolation gasket.

[0014] A second object of the present invention is to provide an ion optical column of an argon ion beam scanning electron microscope, comprising the magnetic shielding device and an ion source as described above, wherein the magnetic shielding device is installed outside the ion source.

[0015] Furthermore, it also includes an angle adjustment element, and the ion source is installed in the sample chamber through the angle adjustment element, so that the incident angle of the ion beam is adjustable.

[0016] Furthermore, the angle adjustment element is an adjustable flange.

[0017] The third object of the present invention is to provide an argon ion beam scanning electron microscope that integrates the above-mentioned ion optical column and electron optical column.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides an argon ion beam scanning electron microscope, an ion optical lens barrel, and a magnetic shielding device, which can effectively isolate the magnetic field generated by the permanent magnet of an electron cyclotron resonance ion source (ECR) to prevent it from interfering with electron beam imaging, thereby improving equipment performance and application scope. The device has a simple and compact structure, and the passive magnetic shielding does not require additional energy supply, is low in cost, and is easy to install and maintain. It has excellent magnetic shielding performance, achieves an extremely low magnetic field level of less than 50nT, and has good application prospects.

[0020] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0022] Figure 1 This is the schematic diagram of the argon ion beam scanning electron microscope;

[0023] Figure 2 Schematic diagram of magnetic shielding device Figure 1 ;

[0024] Figure 3 Schematic diagram of magnetic shielding device Figure 2 ;

[0025] Figure 4 This is a 2D simulation diagram of the magnetic shielding sleeve;

[0026] Figure 5 for Figure 4 A partial enlarged view of .

[0027] In the figure: 1. Argon ion beam scanning electron microscope; 11. Ion optical lens barrel; 110. Magnetic shielding device; 1101. Outermost magnetic shielding tube; 1102. Innermost magnetic shielding tube; 111. Ion source; 112. Angle adjustment element; 113. Permanent magnet; 12. Sample chamber; 13. Sample stage; 14. Electron optical lens barrel; 2. Sample. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the drawings, the shapes and dimensions may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like components.

[0030] In the following description, words such as center, thickness, height, length, front, back, rear, left, right, top, bottom, upper, lower, etc. are defined relative to the structure shown in the drawings. In particular, "height" is equivalent to the dimension from top to bottom, "width" is equivalent to the dimension from left to right, and "depth" is equivalent to the dimension from front to back. They are relative concepts and may change accordingly according to their different positions and different usage states. Therefore, these or other directions should not be interpreted as restrictive terms.

[0031] Terms related to attachment, coupling, and the like (eg, "connected" and "attached") refer to either a fixed or attached relationship between structures, either directly or indirectly, and either movable or rigid attachments or relationships, unless expressly stated otherwise, of the structures to one another through intermediate structures.

[0032] Example 1

[0033] An ion source magnetic shielding device for an argon ion beam scanning electron microscope, such as Figure 1-Figure 3 As shown, the magnetic shielding device 110 includes a multi-layer magnetic shielding structure and a plurality of isolation elements. The multi-layer magnetic shielding structures are spaced and coaxial by the isolation elements. The multi-layer magnetic shielding structure is installed outside the ion source 111 to isolate the magnetic field generated by the permanent magnet of the ion source to prevent interference with electron beam imaging. Further, the isolation element is configured as an isolation gasket.

[0034] The magnetic shielding device 110 is a passive magnetic shielding device used to reduce the magnetic field interference generated by the ion source in the argon ion beam scanning electron microscope.

[0035] Optionally, the ion source is an electron cyclotron resonance ion source (ECR), which has the advantages of high current intensity, high charge state, low emittance, high stability, and long life.

[0036] In some embodiments, the magnetic shielding structure is made of a high magnetic permeability metal shell made of a metal material with high magnetic permeability, such as sodium iron alloy (Perma ll oy) or iron-nickel alloy (Mu-metal). The shell has a certain thickness and shape, completely surrounds the area between the ion source and the electron beam, and ensures isolation from the surrounding environment.

[0037] Install the highly permeable metal housing around the ion source and in good contact with other system components to ensure that the magnetic field cannot enter through the gaps. If necessary, use a sealing device to ensure the sealing between the housing and other components to ensure the stability and reliability of the shielding effect.

[0038] Specifically, the magnetic shielding device uses a sleeve made of a highly magnetically permeable metal material to shield the area between the ion source and the electron beam, and can achieve an extremely low magnetic field level, reducing the magnetic field at the sample 2 to below 50nT during imaging.

[0039] In some embodiments, the multi-layer magnetic shielding structure is configured as two coaxial magnetic shielding tubes, the innermost magnetic shielding tube 1102 is installed outside the ion source 111, and the outermost magnetic shielding tube 1101 is installed outside the innermost magnetic shielding tube 1102. Two isolation elements are used to ensure the spacing and coaxiality between the outermost magnetic shielding tube 1101 and the innermost magnetic shielding tube 1102. Furthermore, the outermost magnetic shielding tube adopts a high magnetic permeability material, and the innermost magnetic shielding tube adopts a high magnetic permeability material.

[0040] In other embodiments, the multi-layer magnetic shielding structure is configured as three magnetic shielding tubes, the innermost magnetic shielding tube is installed outside the ion source, the middle magnetic shielding tube is installed outside the innermost magnetic shielding tube, and the outermost magnetic shielding tube is installed outside the middle magnetic shielding tube. Further, the outermost magnetic shielding tube adopts a high magnetic permeability soft magnet, the middle magnetic shielding tube adopts a high magnetic permeability material, and the innermost magnetic shielding tube adopts a high magnetic permeability material.

[0041] like Figure 2-Figure 3 As shown, the magnetic shielding cylinder is provided with through holes. Furthermore, the positions of the through holes on adjacent magnetic shielding cylinders are not interconnected, so as to isolate the magnetic field generated by the permanent magnet of the ion source and prevent interference with electron beam imaging.

[0042] The number of layers of the multi-layer magnetic shielding structure is simulated and optimized using COMSOL Multiphysics software to obtain the best magnetic shielding effect. Figure 4-Figure 5 As shown. Figure 5 It can be seen that the two-layer magnetic shielding has met the requirement that the magnetic field strength at the imaging position is less than 50nT, so the two-layer magnetic shielding sleeve is selected in this embodiment.

[0043] The present invention adopts a multi-layer magnetic shielding structure to effectively isolate the magnetic field generated by the permanent magnet of the ECR ion source to prevent interference with electron beam imaging; selects materials with high magnetic permeability and low magnetic hysteresis, such as high-purity soft magnetic permalloy, to minimize magnetic field leakage; places the magnetic shielding device between the ECR ion source and the scanning electron microscope (SEM) chamber, and makes fine adjustments according to the magnetic field distribution to ensure the best shielding effect.

[0044] Example 2

[0045] An ion optical column of an argon ion beam scanning electron microscope, such as Figure 1-Figure 3 As shown, the ion optical lens barrel 11 comprises the magnetic shielding device 110 and the ion source 111. The magnetic shielding device is installed outside the ion source. For a detailed description of the magnetic shielding device, reference may be made to the corresponding description in the above magnetic shielding device embodiment, which will not be repeated here.

[0046] The ion source 111 is used to generate an ion beam, the magnetic shielding device 110 is used to isolate the magnetic field generated by the permanent magnet of the ion source 111 to prevent interference with electron beam imaging, and the permanent magnet 113 is used to provide the confining magnetic field required by the ion source 111 .

[0047] In some embodiments, an angle adjustment element 112 is further included, and the ion source is installed on the sample chamber 12 through the angle adjustment element, so that the incident angle of the ion beam is adjustable. Preferably, the angle adjustment element is an adjustable flange.

[0048] Example 3

[0049] An argon ion beam scanning electron microscope 1, such as Figure 1-Figure 3 As shown, the above-mentioned ion optical lens tube 11 and electron optical lens tube 14 are integrated. For the detailed description of the ion source, reference may be made to the corresponding description in the above-mentioned ion source embodiment, which will not be repeated here.

[0050] The working principle of the argon ion beam scanning electron microscope is:

[0051] Ion beam polishing: The sample stage 13 moves to the designated polishing position, and the ion optical lens barrel 11 starts to generate an ion beam. The sample stage 13 can perform continuous rotation, linear reciprocating, swinging and other motion modes to remove the curtain effect, increase the polishing area, and bombard the sample surface with the ion beam.

[0052] Electron beam imaging: The ion optical tube 11 is closed, the sample stage 13 is moved to the specified imaging position, and the electron optical tube 14 emits an electron beam to scan the sample surface. The generated secondary electron signal and backscattered electron signal are collected by the backscattered electron detector and the side secondary electron detector respectively, thereby forming an image.

[0053] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0054] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

[0055] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0056] The specification may be described in the general context of computer-executable instructions executed by a computer, such as program units. Generally, program units include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The specification may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communications network. In a distributed computing environment, program units may be located in local and remote computer storage media, including storage devices.

[0057] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0058] The above description is only an embodiment of this specification and is not intended to limit one or more embodiments of this specification. For those skilled in the art, one or more embodiments of this specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of one or more embodiments of this specification shall be included in the scope of the claims of one or more embodiments of this specification.

Claims

1. An ion source magnetic shielding device for an argon ion beam scanning electron microscope, characterized in that: It includes a multi-layer magnetic shielding structure and multiple isolation elements. The multi-layer magnetic shielding structures are kept spaced and coaxial by the isolation elements. The multi-layer magnetic shielding structure is installed outside the ion source to isolate the magnetic field generated by the permanent magnet of the ion source to prevent interference with electron beam imaging.

2. The ion source magnetic shielding device for an argon ion beam scanning electron microscope according to claim 1, characterized in that: The magnetic shielding structure is made of metal material with high magnetic permeability.

3. The ion source magnetic shielding device for an argon ion beam scanning electron microscope according to claim 1, characterized in that: The multi-layer magnetic shielding structure is configured as two coaxial magnetic shielding cylinders, the innermost magnetic shielding cylinder is installed outside the ion source, and the outermost magnetic shielding cylinder is installed outside the innermost magnetic shielding cylinder.

4. The ion source magnetic shielding device for an argon ion beam scanning electron microscope according to claim 1, characterized in that: The multi-layer magnetic shielding structure is configured as three magnetic shielding tubes, the innermost magnetic shielding tube is installed outside the ion source, the middle magnetic shielding tube is installed outside the innermost magnetic shielding tube, and the outermost magnetic shielding tube is installed outside the middle magnetic shielding tube.

5. An ion source magnetic shielding device for an argon ion beam scanning electron microscope as claimed in claim 3 or 4, characterized in that: The magnetic shielding cylinder is provided with a through hole.

6. The ion source magnetic shielding device for an argon ion beam scanning electron microscope according to claim 5, characterized in that: The positions of the through holes on the adjacent magnetic shielding cylinders are not connected.

7. The ion source magnetic shielding device for an argon ion beam scanning electron microscope according to claim 3, characterized in that: The outermost magnetic shielding tube is made of high magnetic permeability material, and the innermost magnetic shielding tube is made of high magnetic permeability material.

8. The ion source magnetic shielding device for an argon ion beam scanning electron microscope according to claim 4, characterized in that: The outermost magnetic shielding tube adopts high magnetic permeability soft magnet, the middle magnetic shielding tube adopts high magnetic permeability material, and the innermost magnetic shielding tube adopts high magnetic permeability material.

9. The ion source magnetic shielding device for an argon ion beam scanning electron microscope according to claim 1, characterized in that: The isolation element is configured as an isolation gasket.

10. An ion optical lens barrel of an argon ion beam scanning electron microscope, characterized in that: It comprises the magnetic shielding device according to any one of claims 1 to 9 and an ion source, wherein the magnetic shielding device is installed outside the ion source.

11. The ion optical lens barrel of an argon ion beam scanning electron microscope according to claim 10, characterized in that: It also includes an angle adjustment element, and the ion source is installed in the sample chamber through the angle adjustment element, so that the incident angle of the ion beam is adjustable.

12. The ion optical lens barrel of an argon ion beam scanning electron microscope according to claim 11, characterized in that: The angle adjustment element is an adjustable flange.

13. An argon ion beam scanning electron microscope, characterized in that: An ion optical column as described in any one of claims 10 to 12 and an electron optical column are integrated.

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