Method for preparing transmission electron microscope samples using a focused ion beam

Abstract

The present application relates to a kind of transmission electron microscope sample preparation technical field, in particular to the method for preparing transmission electron microscope sample using focused ion beam.The method comprises the following steps: using focused ion beam to extract sample precursor in the region to be measured of the object to be measured;The sample precursor is fixed on sample carrier device;The sample precursor is subjected to several rounds of rough thinning treatment;The sample precursor after rough thinning is subjected to several rounds of fine thinning treatment.The above-mentioned method is novel and unique, fine thinning treatment adopts brand-new partition mode, can process transmission electron microscope sample with large observation area, and there is no warping deformation and crack defect problem.

Description

Technical Field

[0001] This invention relates to the field of transmission electron microscopy (TEM) sample preparation technology, and particularly to a method for preparing TEM samples using a focused ion beam. Background Technology

[0002] Transmission electron microscopy (TEM) is a crucial instrument for studying the microstructure of materials. The study of material microstructure plays a vital role in regulating material properties and understanding their mechanisms. It is no exaggeration to say that the analysis and exploration of the internal structure of materials is paramount in materials science research, occupying at least half of the research cycle. Because TEM performs high-resolution microstructural characterization by collecting the structural information carried by an electron beam passing through the sample, and because electrons are easily scattered or absorbed by the sample material, the electron beam can generally only penetrate ultrathin samples with a thickness of less than 100 nm. Therefore, preparing ultrathin samples suitable for TEM observation is key to high-resolution structural analysis.

[0003] Currently, the main methods for preparing transmission electron microscopy (TEM) samples are ion thinning, electrolytic double-jet, ultrathin sectioning, and focused ion beam (FIB) methods. Ion thinning and electrolytic double-jet methods require grinding and polishing before thinning, a process that demands experienced operators and is generally time-consuming. Furthermore, these two methods are only suitable for bulk materials and cannot thin specific regions of the material. Ultrathin sectioning requires complex pretreatment of the material, has a long preparation cycle, and is difficult to produce samples with high hardness. Compared to the aforementioned methods, FIB has advantages such as high processing efficiency and wide applicability to various materials, especially for preparing TEM samples of specific regions of materials with complex structures, where it has an irreplaceable advantage.

[0004] Focused ion beam (FIB) is a micro / nano fabrication system that uses an electron lens to focus an ion beam into a very small size, enabling micro-cutting. However, when using FIB to prepare transmission electron microscopy (TEM) samples, the observation area (thin region) is often small, for example, 5 μm × 3 μm or smaller. When the observation area is large, the sample prepared by thinning the sample precursor is prone to warping, deformation, and crack defects. Even with certain processing techniques, such as fixing the opposite sides of the sample precursor on the sample support device before thinning, the length × width of the observation area can only be increased to 12 μm × 7 μm, which still cannot meet the structural analysis requirements of TEM samples suitable for large-area observation. Summary of the Invention

[0005] Based on this, the present invention provides a method for preparing transmission electron microscopy samples using a focused ion beam, the technical solution of which is as follows:

[0006] A method for preparing transmission electron microscopy (TEM) samples using a focused ion beam includes the following steps:

[0007] A sample precursor is extracted from the test area of ​​the analyte using a focused ion beam. The sample precursor has a first surface and a second surface with opposite surfaces. The first surface has a first observation area, and the second surface has a second observation area. The first observation area and the second observation area correspond to each other.

[0008] The sample precursor is fixed to the sample carrier, exposing the first and second surfaces;

[0009] The sample precursor is subjected to several rounds of coarse thinning treatment until the distance between the surface located in the first observation area and the surface located in the second observation area is 200nm to 400nm. Each round of coarse thinning treatment independently includes the following steps: treating the first surface and / or the second surface with a focused ion beam.

[0010] The coarsely thinned sample precursor is subjected to several rounds of fine thinning treatment until the distance between the surface located in the first observation area and the surface located in the second observation area is ≤100nm, thus obtaining a transmission electron microscope sample. Each round of fine thinning treatment independently includes the following steps:

[0011] The first observation area after coarse thinning is divided into a first edge region, a first middle region, and a second edge region. The first edge region is connected to the second edge region through the first middle region. The surfaces located in the first and second edge regions are first processed using a focused ion beam, and then the surface located in the first middle region is processed; and / or

[0012] The second observation area after coarse thinning is divided into a third side region, a second middle region, and a fourth side region. The third side region is connected to the fourth side region through the second middle region. The surfaces located in the third and fourth side regions are first processed using a focused ion beam, and then the surface located in the second middle region is processed.

[0013] In some embodiments, the first edge region is divided into several first sub-edge regions, and each first sub-edge region is sequentially connected along the direction close to the first central region until it is connected to the first central region; the second edge region is divided into several second sub-edge regions, and each second sub-edge region is sequentially connected along the direction close to the first central region until it is connected to the first central region.

[0014] The process of first treating the surfaces located in the first and second edge regions using a focused ion beam includes the following steps:

[0015] The surfaces located in several first sub-edge regions and several second sub-edge regions are treated using a focused ion beam. The processing order is as follows: first, the surfaces located in the first sub-edge regions and the second sub-edge regions located far from the first central region are treated, and then the surfaces located in the first sub-edge regions and the second sub-edge regions located close to the first central region are treated.

[0016] In some embodiments, the third side region is divided into several third sub-side regions, and each of the third sub-side regions is sequentially connected along the direction close to the second central region until it is connected to the second central region; the fourth side region is divided into several fourth sub-side regions, and each of the fourth sub-side regions is sequentially connected along the direction close to the second central region until it is connected to the second central region.

[0017] The process of pre-treating the surfaces located in the third and fourth edge regions using a focused ion beam includes the following steps:

[0018] The surfaces located in several third sub-side regions and several fourth sub-side regions are treated using a focused ion beam. The processing order is as follows: first, the surfaces located in the third sub-side regions and the fourth sub-side regions that are far from the second central region are treated, and then the surfaces located in the third sub-side regions and the fourth sub-side regions that are close to the second central region are treated.

[0019] In some embodiments, the parameters for treating the surfaces located in the first edge region, the first middle region, the second edge region, the third edge region, the second middle region, and the fourth edge region using a focused ion beam independently include one or more of the following parameters:

[0020] a) The ion beam voltage is 2kV to 10kV;

[0021] b) The ion beam current is 10 pA to 40 pA;

[0022] c) Bombard the surface to be treated with an ion beam at an incident angle of 82° to 88°.

[0023] In some embodiments, the first surface and the second surface are connected by a plurality of sides, the plurality of sides including a first side and a second side, the first side and the second side being connected.

[0024] Fixing the sample precursor to the sample carrier includes the following steps:

[0025] A focused ion beam is used to cut one side of the sample carrier to form an exposed surface, and the exposed surface includes a mating surface that conforms to the shape formed by the first side and the second side.

[0026] The first and second sides are fixed to the mating surface.

[0027] In some embodiments, the first side is perpendicularly connected to the second side.

[0028] In some embodiments, the cutting satisfies the following condition: the cutting zone formed by the cutting is capable of accommodating the sample precursor.

[0029] In some embodiments, the first surface further includes a first end region located at an end away from the first side or the second side and connected to the first observation area; the second surface further includes a second end region located at an end away from the first side or the second side and connected to the second observation area; the first end region and the second end region correspond to each other.

[0030] In the transmission electron microscope sample, the distance between the surface located in the first end region and the surface located in the second end region is greater than the distance between the surface located in the first observation region and the surface located in the second observation region.

[0031] In some embodiments, the thickness of the first surface thinned by the focused ion beam treatment is 20% to 30% of the thickness of the sample precursor before the current treatment;

[0032] The thickness reduction of the second surface by using focused ion beam treatment is 20% to 30% of the thickness of the sample precursor before the current treatment.

[0033] In some embodiments, the parameters for treating the first and second surfaces using a focused ion beam each independently include one or more of the following parameters:

[0034] a) The ion beam voltage is 15kV to 30kV;

[0035] b) The ion beam current is 45 pA to 1.5 nA;

[0036] c) Bombard the first surface with an ion beam at an incident angle of 88.5° to 89.5° or bombard the second surface with an ion beam at an incident angle of 88.5° to 89.5°.

[0037] In some embodiments, the extraction of sample precursors from the test region of the analyte using a focused ion beam includes the following steps:

[0038] The area to be tested is determined, and a protective layer is formed on the area to be tested;

[0039] Retain the connection between a portion of the material in the area to be tested and the material in the surrounding area, and sever the connection between the remaining side and the material in the surrounding area.

[0040] The extraction device is fixed to the side of the substance in the area to be tested that is away from the retention side.

[0041] The connection between the remaining side of the substance in the test area and the substance in the surrounding area is severed, and the connection between the bottom of the substance in the test area and the substance in the surrounding area is severed to obtain the sample precursor.

[0042] In some embodiments, the area of ​​the first observation region is 240 μm.2 ~450μm 2 The area of ​​the second observation region is 240 μm. 2 ~450μm 2 .

[0043] Compared with traditional solutions, the present invention has the following advantages:

[0044] The method for preparing transmission electron microscopy (TEM) samples using focused ion beam (FIB) provided by this invention can produce TEM samples suitable for large observation areas and free from warping, deformation, and crack defects. The key to this method lies in performing several rounds of coarse thinning on the sample precursor, followed by several rounds of fine thinning. In particular, during the fine thinning process, the first and / or second observation areas are divided, with the edge areas processed first, followed by the central area. This solves the problem of warping, deformation, and crack defects that easily occur in TEM samples with large observation areas after thinning, thus meeting the high-resolution structural analysis requirements of samples with large observation areas. Therefore, the above method has significant scientific and practical value. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention and to more completely understand the present invention and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a scanning electron microscope image of the sample stage after the pre-cutting in step two of Example 1 (the stage tilt angle is 0°).

[0047] Figure 2 This is a scanning electron microscope image of the sample stage after the pre-cutting in step two of Example 1 (the stage tilt angle is 54°).

[0048] Figure 3 This is a scanning electron microscope image of step three in Example 1, after one end of the nanomanipulator is welded to the material in the area to be tested.

[0049] Figure 4 This is a scanning electron microscope image of the sample precursor in step three of Example 1 after it has been lifted by the nanomanipulator;

[0050] Figure 5 This is a scanning electron microscope image of step three of embodiment one, in which one side of the FIB special support net protrusion claw is cut into an L-shaped exposed surface.

[0051] Figure 6This is a scanning electron microscope image taken after step three of Example 1, in which the slice of the area to be detected is transferred into the stepped opening of the FIB special support network using a nanomanipulator, and Pt is deposited by ion beam to tightly weld and fix the lower end and side end of the slice to the upper surface of the lower step and the side surface of the upper step, respectively.

[0052] Figure 7 This is a scanning electron microscope image of the sample precursor fixed on the FIB special support mesh in step three of Example 1;

[0053] Figure 8 This is a schematic diagram of the sample precursor thinning process in step five of Example 1; wherein, (a) is a scanning electron microscope image of the sample precursor when it is tilted to 46° before the sample stage is rotated 180° around its axis; (b) is a scanning electron microscope image of the sample precursor when it is tilted to 46° after the sample stage is rotated 180° around its axis; (c) is a model diagram corresponding to Figure (a) and Figure (b), and each dashed box corresponds to the area after the first observation area and the second observation area are divided;

[0054] Figure 9 The image shown is a scanning electron microscope (SEM) image of the transmission electron microscope (TEM) sample from step five of Example 1. The dashed box indicates the observation area.

[0055] Figure 10 This is a transmission electron microscope (TEM) image of the observation area of ​​the sample in step five of Example 1.

[0056] Figure 11 This is a high-resolution transmission electron microscope (TEM) image of the interlayer interface in the observation area of ​​the TEM sample in step five of Example 1. Detailed Implementation

[0057] The present invention will be further described in detail below with reference to specific embodiments. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0059] the term

[0060] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0061] In this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. In this invention, "a number of" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0062] In this invention, the terms "optionally," "optionally," and "optional" refer to options that are optional, meaning they are selected from either "with" or "without." If multiple "optional" options appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" option is independent.

[0063] In this invention, terms such as "further," "even more," and "particularly" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this invention.

[0064] In this invention, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0065] In this invention, the incident angle refers to the angle between the beam current of the ion beam and the normal of the surface when the ion beam bombards the surface to be treated.

[0066] Microstructural analysis of materials plays a crucial role in the regulation of material properties and the development of new materials. This analysis relies on transmission electron microscopy (TEM), which demands extremely precise sample size and condition. Obtaining high-quality electron micrographs depends entirely on the preparation of high-quality samples suitable for TEM observation. Currently, focused ion beam (FIB) has become an important method for obtaining high-quality TEM samples due to its high precision and efficiency. However, TEM samples prepared with FIB often have a small observation area. When the observation area is large, the thinned sample is prone to warping, deformation, and cracking defects.

[0067] One embodiment of the present invention provides a method for preparing transmission electron microscopy (TEM) samples using a focused ion beam. This method is novel and unique, capable of producing TEM samples with a large observation area without warping, deformation, or crack defects, thus providing technical support for large-area structural analysis of materials. The method includes the following steps:

[0068] A sample precursor is extracted from the test area of ​​the analyte using a focused ion beam. The sample precursor has a first surface and a second surface with opposite surfaces. The first surface has a first observation area, and the second surface has a second observation area. The first observation area and the second observation area correspond to each other.

[0069] The sample precursor is fixed to the sample carrier, exposing the first and second surfaces;

[0070] The sample precursor is subjected to several rounds of coarse thinning treatment until the distance between the surface located in the first observation area and the surface located in the second observation area is 200nm to 400nm. Each round of coarse thinning treatment independently includes the following steps: treating the first surface and / or the second surface with a focused ion beam.

[0071] The coarsely thinned sample precursor is subjected to several rounds of fine thinning treatment until the distance between the surface located in the first observation area and the surface located in the second observation area is ≤100nm, thus obtaining a transmission electron microscope sample. Each round of fine thinning treatment independently includes the following steps:

[0072] The first observation area after coarse thinning is divided into a first edge region, a first middle region, and a second edge region. The first edge region is connected to the second edge region through the first middle region. The surfaces located in the first and second edge regions are first processed using a focused ion beam, and then the surface located in the first middle region is processed; and / or

[0073] The second observation area after coarse thinning is divided into a third side region, a second middle region, and a fourth side region. The third side region is connected to the fourth side region through the second middle region. The surfaces located in the third and fourth side regions are first processed using a focused ion beam, and then the surface located in the second middle region is processed.

[0074] The key point of this method is that the sample precursor undergoes several rounds of coarse thinning followed by several rounds of fine thinning. In particular, during the fine thinning process, the first and / or second observation areas are divided, with the edge areas processed first, followed by the central area. This solves the problem of warping, deformation, and cracking defects that easily occur in transmission electron microscopy samples with large observation areas after thinning, and can meet the high-resolution structural analysis requirements of samples with large observation areas. Therefore, the above method has significant scientific and practical value.

[0075] In this embodiment, the area of ​​the first observation region can be 240 μm. 2 ~450μm 2 The area of ​​the second observation region can be 240 μm. 2 ~450μm 2 .

[0076] Further optionally, when the first observation area and the second observation area are rectangular, the length × width of the first observation area and the second observation area can reach (20μm~25μm)×(12μm~18μm).

[0077] Optionally, in the above method, the extraction of the sample precursor from the test region of the analyte using a focused ion beam includes the following steps:

[0078] The area to be tested is determined, and a protective layer is formed on the area to be tested;

[0079] Retain the connection between a portion of the material in the area to be tested and the material in the surrounding area, and sever the connection between the remaining side and the material in the surrounding area.

[0080] The extraction device is fixed to the side of the substance in the area to be tested that is away from the retention side.

[0081] The connection between the remaining side of the substance in the test area and the substance in the surrounding area is severed, and the connection between the bottom of the substance in the test area and the substance in the surrounding area is severed to obtain the sample precursor.

[0082] Alternatively, the measurement region can be determined using the following two methods based on the resistivity of the object being measured:

[0083] When the resistivity of the analyte is <450 nΩ·m, the test area of ​​the analyte is selected using secondary electron or backscatter mode under the electron beam window of the FIB-SEM dual-beam system (sample stage tilt angle 0°), specifically at an electron beam voltage of 5 kV to 30 kV.

[0084] When the resistivity of the analyte is ≥450 nΩ·m, the method further includes a gold sputtering process. After the gold sputtering process, the analyte region is selected using secondary electron or backscattering mode under the electron beam window of a FIB-SEM dual-beam system (sample stage tilt angle 0°) and a voltage of 5 kV to 30 kV. The purpose of the gold sputtering is to avoid processing window drift during transmission electron microscopy sample preparation. Optionally, the thickness of the gold sputtering process is 5 nm to 50 nm.

[0085] Optionally, forming a protective layer over the area to be tested includes the following steps:

[0086] First, an electron beam is used to deposit a protective material on the area to be tested to form a first protective layer. Then, an ion beam is used to deposit a protective material on the first protective layer to form a second protective layer.

[0087] Alternatively, the protective material may be Pt or C.

[0088] Using electron beam deposition of protective material followed by ion beam deposition of protective material has the following effects: (1) It avoids damage to the test area during ion beam deposition of protective material. When there are nanostructures to be analyzed on the surface of the test area, ion beam deposition of protective material may slightly damage the surface structure. In contrast, electron beam deposition of protective material causes minimal damage to the surface and can effectively reduce or avoid structural damage to the surface caused by subsequent ion beam deposition of protective material; (2) It facilitates the rapid determination of the test area location under the ion beam window. Because the resolution of focused ion beam is lower than that of focused electron beam, when the microstructure of the test object is fine, it may not be easy to quickly determine the test area location under the ion beam window, increasing the risk of damage to the test area by the ion beam. When the test area is first deposited with protective material by electron beam deposition, the location of the test area can be quickly and accurately determined under the ion beam window.

[0089] In this embodiment, under the electron beam window (sample stage tilt angle 0°), specifically with an electron beam voltage of 1kV to 20kV and an electron beam current of 10pA to 8nA, a first protective layer is deposited with a thickness of 0.02μm to 0.2μm. The voltage is then returned to 5kV to 30kV, and the sample is repositioned to the calibrated test area.

[0090] Under the ion beam window (sample stage tilt angle 54°), specifically with an ion beam voltage of 10kV to 30kV and an ion beam current of 5pA to 100pA, a second protective layer is deposited with a thickness of 1μm to 2μm.

[0091] After the protective layer is formed, a focused ion beam is used to retain the connection between a portion of the material in the test area and the material in the surrounding area, while severing the connection between the remaining side and the material in the surrounding area.

[0092] In this embodiment, the area to be tested with the deposited protective layer is facing the ion beam (sample stage tilt angle 54°), and the connection between the remaining side surface and the surrounding area is severed when the ion beam voltage is 20kV to 30kV and the ion beam current is 11nA to 80nA.

[0093] Understandably, when the sample precursor is a cuboid, one side is retained to maintain its connection with the surrounding material, while the connections of the remaining three sides to the surrounding material are severed. Specifically, the two sides in the width direction are cut with wedge-shaped ramps, one side in the long side direction is cut perpendicularly, and the remaining side is left uncut. From a top-down view, this creates a U-shaped cutting area.

[0094] The extraction device is fixed to the side of the substance in the area to be tested that is away from the side that is to be retained.

[0095] In this embodiment, the test area with the deposited protective layer is at a 54° angle to the ion beam direction (sample stage tilt angle 0°). With an ion beam voltage of 10kV to 30kV and an ion beam current of 5pA to 100pA, one end of the extraction device is welded to the material in the test area by depositing the protective material.

[0096] The connection between the remaining side of the material in the test area and the material in the surrounding area is severed, and the connection between the bottom of the material in the test area and the material in the surrounding area is severed.

[0097] In this embodiment, the test area of ​​the deposited protective layer is at a 54° angle to the ion beam direction (sample stage tilt angle 0°). With an ion beam voltage of 20kV to 30kV and an ion beam current of 0.28nA to 12nA, the connection between the retained side of the material in the test area and the material in the surrounding area is severed, and the connection between the bottom of the material in the test area and the material in the surrounding area is severed, thereby achieving complete separation of the material in the test area from the material in the surrounding area.

[0098] After completely cutting and separating the substance in the area to be tested from the substance in the surrounding area, the sample precursor is obtained. Holding the other end of the extraction device, the sample precursor is slowly lifted.

[0099] Optionally, the extraction device is a nanomanipulator.

[0100] In the above method, welding one end of the extraction device to the material in the test area and then completely severing and separating the material in the test area from the surrounding material has the following effects: It avoids the potential shaking or collapse of the material in the test area due to its large size / weight. This is because if the connection between the remaining side (or part of the remaining side) or bottom of the material in the test area and the surrounding material is severed before welding the extraction device, the material in the test area may shake or collapse, making it impossible for the subsequent sample precursor to be successfully lifted by the extraction device.

[0101] In this embodiment, the sample precursor has a first surface and a second surface opposite to each other, and the sample precursor is fixed to the sample carrier device.

[0102] Optionally, the first surface and the second surface are connected by a plurality of side surfaces, the plurality of side surfaces including a first side surface and a second side surface, the first side surface and the second side surface being connected.

[0103] Fixing the sample precursor to the sample carrier includes the following steps:

[0104] A focused ion beam is used to cut one side of the sample carrier to form an exposed surface, and the exposed surface includes a mating surface that conforms to the shape formed by the first side and the second side.

[0105] The first and second sides are fixed to the mating surface.

[0106] Understandably, due to the change in observation angle, the aforementioned "several sides" including the first and second sides differs from the definitions of the "partial sides" and "remaining sides" mentioned above when extracting the sample precursor. The aforementioned "several sides" including the first and second sides refers to the side connecting the first and second surfaces. The aforementioned "partial sides" and "remaining sides" mentioned when extracting the sample precursor refers to the side connecting the top and bottom of the substance in the test area, defining the surface of the test area as the top.

[0107] In this embodiment, one side of the sample carrier is at a 54° angle to the ion beam (sample stage tilt angle 0°). The side of the sample carrier is cut at an ion beam voltage of 20kV to 30kV and an ion beam current of 12nA to 100nA to form an exposed surface.

[0108] Optionally, the sample carrier is a FIB-specific support net, and one side of the sample carrier can be one side of the protruding claw of the FIB-specific support net.

[0109] Optionally, the first side and the second side are perpendicularly connected.

[0110] Optionally, the cutting satisfies the following condition: the cutting zone formed by the cutting is able to accommodate the sample precursor.

[0111] Understandably, when the sample precursor is a cuboid, the first side is perpendicularly connected to the second side. After the sample carrier is cut, the side view of the exposed surface is L-shaped.

[0112] Optionally, the sample precursor is transferred to the mating surface of the cut sample carrier using an extraction device, and a protective material is deposited to weld and fix the first and second side surfaces to the mating surface. Optionally, the ion beam voltage of the protective material is 10kV to 30kV, and the ion beam current is 20pA to 280pA.

[0113] After welding and fixing the first and second sides to the mating surface, the connection between the extraction device and the sample precursor is severed using an ion beam, resulting in a sample precursor fixed on the sample carrier. Optionally, the ion beam voltage for severing the connection between the extraction device and the sample precursor is 20kV to 30kV, and the ion beam current is 0.28nA to 12nA.

[0114] In the above method, one side of the sample support device is first cut to form an exposed surface, and the exposed surface includes a mating surface that matches the shape formed by the first side and the second side. Then, the first side and the second side are fixed to the mating surface. This has the following effects: the sample precursor will not collapse due to its large weight, and it is beneficial to prevent warping deformation and crack defects when the sample precursor is subjected to coarse and fine thinning processes. This unique sample precursor fixing method is beneficial for preparing transmission electron microscope samples with ultra-large observation areas.

[0115] Optionally, the first surface further includes a first end region located at an end away from the first side or the second side and connected to the first observation area; the second surface further includes a second end region located at an end away from the first side or the second side and connected to the second observation area; the first end region and the second end region correspond to each other.

[0116] In the transmission electron microscope sample, the distance between the surface located in the first end region and the surface located in the second end region is greater than the distance between the surface located in the first observation region and the surface located in the second observation region.

[0117] Setting up a first end region and a second end region also helps to reduce warping and crack defects in transmission electron microscope samples.

[0118] After fixing the sample precursor to the sample carrier, the sample precursor is subjected to several rounds of coarse thinning treatment.

[0119] Optionally, each round of coarse thinning treatment is mainly used to thin the surface located in the first observation area and the second observation area. It can thin the surface located in the first end area and the second end area, or it can leave the surface in the first end area and the second end area unthinned.

[0120] Optionally, the thickness reduction of the first surface by using focused ion beam treatment is 20% to 30% of the thickness of the sample precursor before the current treatment;

[0121] The thickness reduction of the second surface by using focused ion beam treatment is 20% to 30% of the thickness of the sample precursor before the current treatment.

[0122] Understandably, the thinning thickness here refers to the thinning thickness of the surface of the first or second observation area.

[0123] Optionally, the thinning of the first and second surfaces can be performed alternately.

[0124] Optionally, the parameters for treating the first and second surfaces using a focused ion beam each independently include one or more of the following parameters:

[0125] a) The ion beam voltage is 15kV to 30kV;

[0126] b) The ion beam current is 45 pA to 1.5 nA;

[0127] c) Bombard the first surface with an ion beam at an incident angle of 88.5° to 89.5° or bombard the second surface with an ion beam at an incident angle of 88.5° to 89.5°.

[0128] In this embodiment, the sample precursor fixed on the sample support device is tilted so that the ion beam bombards the first and second surfaces at an incident angle of 88.5° to 89.5° (since the sample precursor is fixed to the side of the sample support device, in actual operation, the sample stage can be tilted to 52.5° to 53.5° and 54.5° to 55.5° respectively to achieve the above incident angle). With an ion beam voltage of 15kV to 30kV and an ion beam current of 45pA to 1.5nA, several rounds of coarse thinning treatment are performed on the first and second observation areas on both sides of the sample precursor. Specifically, the first and second end regions each retain a 2μm to 5μm area without thinning. The first round of coarse thinning includes: tilting the sample stage to 52.5 to 53.5° to thin the first surface. After the thickness is reduced by 20% to 30%, the sample stage is tilted to 54.5 to 55.5° to thin the second surface, reducing the thickness by another 20% to 30%. The remaining rounds of coarse thinning include: repeating the first round of coarse thinning until the distance between the surface in the first observation area and the surface in the second observation area is 200nm to 400nm.

[0129] Through various rounds of coarse thinning processes, the thickness of the sample precursor is rapidly reduced by utilizing larger ion beam voltages and ion beam currents.

[0130] After each round of coarse thinning, the sample precursor undergoes fine thinning. During fine thinning, the first observation area and / or the second observation area are divided into two zones, with the edge zone processed first, followed by the middle zone.

[0131] Optionally, the parameters for treating the surfaces located in the first edge region, first middle region, second edge region, third edge region, second middle region, and fourth edge region using focused ion beam treatment each independently include one or more of the following parameters:

[0132] a) The ion beam voltage is 2kV to 10kV;

[0133] b) The ion beam current is 10 pA to 40 pA;

[0134] c) Bombard the surface to be treated with an ion beam at an incident angle of 82° to 88°.

[0135] The aforementioned fine thinning process employs a novel zoning model, utilizing a smaller ion beam voltage and current to process the edge region first, followed by the central region, thinning each zone sequentially. This allows the fine thinning process to be performed within a relatively small area, avoiding the uneven thinning that may occur with large-area thinning, as well as the resulting warping and cracks in the observation area.

[0136] The above-mentioned coarse and fine thinning processes for the sample precursor can improve the thinning efficiency and ensure high observation quality in the observation area.

[0137] Optionally, the first edge region is divided into several first sub-edge regions, and each first sub-edge region is connected in sequence along the direction close to the first middle region until it is connected to the first middle region; the second edge region is divided into several second sub-edge regions, and each second sub-edge region is connected in sequence along the direction close to the first middle region until it is connected to the first middle region.

[0138] The process of first treating the surfaces located in the first and second edge regions using a focused ion beam includes the following steps:

[0139] The surfaces located in several first sub-edge regions and several second sub-edge regions are treated using a focused ion beam. The processing order is as follows: first, the surfaces located in the first sub-edge regions and the second sub-edge regions located far from the first central region are treated, and then the surfaces located in the first sub-edge regions and the second sub-edge regions located close to the first central region are treated.

[0140] Optionally, the third side region is divided into several third sub-side regions, and each of the third sub-side regions is connected in sequence along the direction close to the second central region until it is connected to the second central region; the fourth side region is divided into several fourth sub-side regions, and each of the fourth sub-side regions is connected in sequence along the direction close to the second central region until it is connected to the second central region.

[0141] The process of pre-treating the surfaces located in the third and fourth edge regions using a focused ion beam includes the following steps:

[0142] The surfaces located in several third sub-side regions and several fourth sub-side regions are treated using a focused ion beam. The processing order is as follows: first, the surfaces located in the third sub-side regions and the fourth sub-side regions that are far from the second central region are treated, and then the surfaces located in the third sub-side regions and the fourth sub-side regions that are close to the second central region are treated.

[0143] Understandably, the first and second side regions can each be independently divided into 1, 2, 3, or 4 sub-side regions, and the third and fourth side regions can each be independently divided into 1, 2, 3, or 4 sub-side regions. The processing order is as described above.

[0144] In one example, the first edge region is divided into a first sub-edge region and a second sub-edge region, the first sub-edge region being connected to the first middle region through the second sub-edge region, and the second edge region is divided into a third sub-edge region and a fourth sub-edge region, the fourth sub-edge region being connected to the first middle region through the third sub-edge region.

[0145] The process of first treating the surfaces located in the first edge region and the second edge region using a focused ion beam includes the following steps:

[0146] The surfaces located in the first and fourth sub-side regions are first treated using a focused ion beam, and then the surfaces located in the second and third sub-side regions are treated.

[0147] In one example, the third side region is divided into a fifth sub-side region and a sixth sub-side region, the fifth sub-side region being connected to the second middle region through the sixth sub-side region; the fourth side region is divided into a seventh sub-side region and an eighth sub-side region, the eighth sub-side region being connected to the second middle region through the seventh sub-side region.

[0148] The process of first treating the surfaces located in the third and fourth edge regions using a focused ion beam includes the following steps:

[0149] The surfaces located in the fifth and eighth sub-side regions are first treated using a focused ion beam, and then the surfaces located in the sixth and seventh sub-side regions are treated.

[0150] In one example, the first edge region is divided into a ninth sub-edge region, a tenth sub-edge region, and an eleventh sub-edge region. The ninth sub-edge region is connected to the tenth sub-edge region, the tenth sub-edge region is connected to the eleventh sub-edge region, and the eleventh sub-edge region is connected to the first middle region. The second edge region is divided into a twelfth sub-edge region, a thirteenth sub-edge region, and a fourteenth sub-edge region. The twelfth sub-edge region is connected to the first middle region, the thirteenth sub-edge region is connected to the twelfth sub-edge region, and the fourteenth sub-edge region is connected to the thirteenth sub-edge region.

[0151] The process of first treating the surfaces located in the first edge region and the second edge region using a focused ion beam includes the following steps:

[0152] The surfaces located in the ninth and fourteenth sub-side regions are first treated using a focused ion beam, then the surfaces located in the tenth and thirteenth sub-side regions are treated, and then the surfaces located in the eleventh and twelfth sub-side regions are treated.

[0153] In one example, the third border region is divided into the fifteenth, sixteenth, and seventeenth sub-border regions, with the fifteenth sub-border region connected to the sixteenth sub-border region, the sixteenth sub-border region connected to the seventeenth sub-border region, and the seventeenth sub-border region connected to the second middle region. The fourth border region is divided into the eighteenth, nineteenth, and twentieth sub-border regions, with the eighteenth sub-border region connected to the second middle region, the nineteenth sub-border region connected to the eighteenth sub-border region, and the twentieth sub-border region connected to the nineteenth sub-border region.

[0154] The process of first treating the surfaces located in the third and fourth edge regions using a focused ion beam includes the following steps:

[0155] The surfaces located in the fifteenth and twentieth sub-side regions are first treated using a focused ion beam, then the surfaces located in the sixteenth and nineteenth sub-side regions are treated, and then the surfaces located in the seventeenth and eighteenth sub-side regions are treated.

[0156] In this embodiment, the sample precursor fixed on the sample support device is tilted so that the ion beam bombards the surface to be treated at an incident angle of 82° to 88° (since the sample precursor is fixed to the side of the sample support device, the sample stage can be tilted to 46° to 52° in actual operation to achieve the above incident angle). Specifically, the sample stage is tilted to 46° to 52°, and the first observation area of ​​the sample precursor is thinned at an ion beam voltage of 2kV to 10kV and an ion beam current of 10pA to 40pA. The first observation area is divided into a first sub-side area, a second sub-side area, a first middle area, a third sub-side area, and a fourth sub-side area, as described above. Specifically, the thinning process of the first observation area includes: tilting the sample stage to 46° to 52°, using a focused ion beam to first treat the surfaces located in the first and fourth sub-side areas, then treating the surfaces located in the second and third sub-side areas, and then treating the surface located in the first middle area. When the distance between the surfaces of the first and second observation areas is ≤200 nm, the sample stage is tilted to face the ion beam direction (i.e., tilted to 54°), then rotated 180° around its axis to tilt the sample stage to 46–52°. With an ion beam voltage of 2 kV–10 kV and an ion beam current of 10 pA–40 pA, the second observation area of ​​the sample precursor is thinned. The second observation area is divided into a fifth sub-side region, a sixth sub-side region, a second central region, a seventh sub-side region, and an eighth sub-side region, as described above. Specifically, the thinning process of the second observation area includes: tilting the sample stage to 46–52°, using a focused ion beam to first process the surfaces located in the fifth and eighth sub-side regions, then the surfaces located in the sixth and seventh sub-side regions, and then the surface located in the second central region, until the distance between the surfaces of the first and second observation areas is ≤100 nm, resulting in a transmission electron microscope sample with an ultra-large observation area.

[0157] This embodiment proposes a novel method for processing transmission electron microscopy (TEM) samples based on focused ion beams, which can increase the effective observation area of ​​TEM samples to 240 μm. 2 ~450μm 2 When the observation area is rectangular, the length × width of the observation area can reach (20μm~25μm)×(12μm~18μm).

[0158] Furthermore, compared to the method of fixing the two opposite sides of the connecting first and second surfaces of the sample precursor to the sample support device and then performing non-partitioned thinning (effective observation area length × width 12μm × 7μm), the observation area of ​​the method in this embodiment is increased by nearly 4 times. Compared to the method of fixing one side of the connecting first and second surfaces of the sample precursor to the sample support device and leaving the other side suspended, and then performing non-partitioned thinning (effective observation area length × width ≤ 5μm × 3μm), the observation area of ​​the method in this embodiment is increased by nearly 20 times.

[0159] This embodiment utilizes a method for preparing transmission electron microscopy samples with ultra-large observation areas using focused ion beams. This method has broad application prospects and important practical significance for rapidly and accurately obtaining high-resolution structures of materials over large areas, such as the statistics of fine grain size and orientation, large-size multiphase grain interfaces, the microstructure of weld heat-affected zones, and the high-resolution structures of complex semiconductor devices.

[0160] The test object in this embodiment can be a complex multilayer structure material.

[0161] The following detailed description is provided in conjunction with specific embodiments. Unless otherwise specified, all raw materials and instruments used in the following embodiments are commercially available. Unless otherwise specified, all processes involved are conventionally selected by those skilled in the art.

[0162] Example 1: Preparation of Transmission Electron Microscopy Samples of Complex Multilayer Materials

[0163] Combination Figures 1 to 11 This embodiment provides a method for preparing transmission electron microscopy (TEM) samples of complex multilayer materials using a focused ion beam. The steps are as follows:

[0164] I. Selection and protection of the area to be tested:

[0165] Under the electron beam window of the FIB-SEM dual-beam system (sample stage tilt angle 0°), specifically with an electron beam voltage of 5 kV, the test area is selected using secondary electron mode. With an electron beam voltage of 1 kV and an electron beam current of 5 nA, Pt is deposited on the test area to form a first protective layer with a thickness of 0.1 μm. The voltage is then returned to 5 kV, and the test area is repositioned to its calibrated location. Under the ion beam window (sample stage tilt angle 54°), specifically with an ion beam voltage of 30 kV and an ion beam current of 80 pA, Pt is deposited on the first protective layer to form a second protective layer with a thickness of 1 μm, resulting in a test area protected by Pt at the top.

[0166] II. Pre-cutting of the material in the test area:

[0167] With the top Pt-protected test area facing the ion beam (sample stage tilt angle 54°), under the conditions of ion beam voltage of 30kV and ion beam current of 45nA, retain the connection between one side and the surrounding material. Use the focused ion beam to cut off the connection between the remaining three sides and the surrounding material. Specifically, the two sides in the width direction are cut with wedge-shaped ramps, one side in the long side direction is cut vertically, and the remaining side is not cut.

[0168] Viewed from above (sample stage tilt angle 0°), as Figure 1 As shown, a U-shaped cutting area is formed. Viewed from the side (sample stage tilt angle is 54°), as... Figure 2 As shown.

[0169] III. Extraction and Welding Fixation of Sample Precursors:

[0170] The Pt-protected test area is positioned at a 54° angle to the ion beam (sample stage tilt angle 0°). Under the ion beam window, the nanomanipulator is moved to the side of the test area away from the retention side. With an ion beam voltage of 30 kV and an ion beam current of 80 pA, one end of the nanomanipulator is welded to the test area material by Pt deposition. Figure 3 As shown.

[0171] Under the conditions of ion beam voltage of 30kV and ion beam current of 12nA, first disconnect the connection between the retained side of the substance in the target area and the surrounding substance, then disconnect the connection between the bottom of the substance in the target area and the surrounding substance. Holding the other end of the extraction device, slowly lift the sample precursor, as... Figure 4 As shown, the sample precursor has a first surface and a second surface opposite to each other. The first surface has a first observation area, and the second surface has a second observation area. The first observation area and the second observation area correspond to each other. The first surface and the second surface are connected by four sides, including a first side and a second side, which are perpendicularly connected.

[0172] One side of the FIB-specific support mesh protrusion is angled at 54° to the ion beam (sample stage tilt angle 0°). Under conditions of ion beam voltage of 30kV and ion beam current of 45nA, the ion beam is used to cut one side of the FIB-specific support mesh protrusion into an L-shaped exposed surface. The exposed surface includes a mating surface that conforms to the shape formed by the first and second sides, such as... Figure 5 As shown.

[0173] The sample precursor was transferred to the cutting zone created by the aforementioned cutting process using a nanomanipulator. Then, under conditions of an ion beam voltage of 30 kV and an ion beam current of 80 pA, Pt was deposited to weld and fix the first and second sides of the sample precursor to the mating surface. Figure 6 As shown. At this time, the sample precursor is fixed to the sample carrier and the first and second surfaces are exposed.

[0174] Under the conditions of ion beam voltage of 30kV and ion beam current of 1.5nA, the connection between the nanomanipulator and the sample precursor was severed using the ion beam, resulting in a sample precursor fixed on a FIB-specific support mesh, as shown below. Figure 7 As shown.

[0175] IV. Coarse thinning of sample precursors:

[0176] A non-thinned region of 3μm to 4μm is retained at both ends, and the observation area is coarsely thinned. Specifically: Under the conditions of ion beam voltage of 30kV and ion beam current of 1.5nA, the sample stage is tilted to 53° to thin the first observation area. After the thickness is reduced by 30%, the sample stage is tilted to 55° to thin the second observation area, reducing the thickness by another 30%. Under the conditions of ion beam voltage of 30kV and ion beam current of 280pA, the sample stage is tilted to 53.3° to thin the first observation area. After the thickness is reduced by 30%, the sample stage is tilted to 54.7° to thin the second observation area, reducing the thickness by another 30%. Under the conditions of ion beam voltage of 30kV and ion beam current of 80pA, the sample stage is tilted to 53.3° to thin the first observation area. After the thickness is reduced by 25%, the sample stage is tilted to 54.7° to thin the second observation area, reducing the thickness by another 25%. A sample precursor with an observation area thickness of 270nm is obtained.

[0177] V. Thinning of sample precursors:

[0178] The observation area was thinned. Specifically: see [link to relevant documentation]. Figure 8 The first observation area is divided into a first sub-side region, a second sub-side region, a first middle region, a third sub-side region, and a fourth sub-side region. The second observation area is divided into a fifth sub-side region, a sixth sub-side region, a second middle region, a seventh sub-side region, and an eighth sub-side region, as described above. With an ion beam voltage of 5 kV and an ion beam current of 20 pA, the sample stage is tilted to 46°. The surfaces located in the first and fourth sub-side regions are processed first, followed by the surfaces in the second and third sub-side regions, and then the surface in the first middle region. When the observation area thickness is reduced to 180 nm, the sample stage is tilted to face the ion beam direction (i.e., tilted to 54°), rotated 180° around its axis, and then tilted to 46°. The surfaces located in the fifth and eighth sub-side regions are processed first, followed by the surfaces in the sixth and seventh sub-side regions, and then the surface in the second middle region, resulting in a transmission electron microscope sample with an observation area thickness of 90 nm. See [link to relevant documentation]. Figure 9As can be seen, the observation area of ​​the prepared transmission electron microscope sample is rectangular, with a length × width of 22.7 μm × 14.7 μm, and the observation area has an extremely large size.

[0179] The obtained transmission electron microscopy (TEM) samples were analyzed using TEM. See [reference needed]. Figure 10 and 11 , Figure 10 This is a transmission electron microscope (TEM) image. Figure 11 This is a high-resolution transmission electron microscope (TEM) image of the interlayer interface. From... Figure 10 The complete multilayer structure of the sample can be clearly observed from... Figure 11 The layers near the interface are interpenetrating and interwoven, and clear lattice fringes are visible within each layer. This demonstrates that the method proposed in this embodiment for preparing transmission electron microscopy (TEM) samples using focused ion beams has excellent electron microscopy characterization results.

[0180] The complex multilayer material in this embodiment has an extremely complex interlayer interface structure, and conventional transmission electron microscopy (TEM) sample preparation methods cannot obtain samples with intact layer structures, uniform thin regions, and large sizes. This embodiment yields TEM samples with intact layer structures and large observation areas.

[0181] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0182] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing transmission electron microscopy samples using a focused ion beam, characterized in that, Includes the following steps: A sample precursor is extracted from the target region of the analyte using a focused ion beam. The sample precursor has a first surface and a second surface opposite to each other, which are connected by a plurality of side surfaces, including a first side surface and a second side surface, which are connected to each other. The first surface has a first observation area with an area of ​​240 μm. 2 ~450 μm 2 The second surface has a second observation area with an area of ​​240 μm. 2 ~450 μm 2 The first observation area corresponds to the second observation area; A focused ion beam is used to cut one side of the sample carrier to form an exposed surface, and the exposed surface includes a mating surface that matches the shape formed by the first side and the second side; the first side and the second side are fixed to the mating surface to fix the sample precursor to the sample carrier and expose the first surface and the second surface. The sample precursor is subjected to several rounds of coarse thinning treatment until the distance between the surface located in the first observation area and the surface located in the second observation area is 200 nm to 400 nm. Each round of coarse thinning treatment independently includes the following steps: treating the first surface and / or the second surface with a focused ion beam. The coarsely thinned sample precursor is subjected to several rounds of fine thinning until the distance between the surface located in the first observation area and the surface located in the second observation area is ≤100 nm, thus obtaining a transmission electron microscope sample. Each round of fine thinning independently includes the following steps: The first observation area after coarse thinning is divided into a first edge region, a first middle region, and a second edge region. The first edge region is connected to the second edge region through the first middle region. The surfaces located in the first and second edge regions are first processed using a focused ion beam, and then the surface located in the first middle region is processed; and / or The second observation area after coarse thinning is divided into a third side region, a second middle region, and a fourth side region. The third side region is connected to the fourth side region through the second middle region. The surfaces located in the third and fourth side regions are first processed using a focused ion beam, and then the surface located in the second middle region is processed.

2. The method for preparing transmission electron microscopy samples using a focused ion beam according to claim 1, characterized in that, The first edge region is divided into several first sub-edge regions, and each first sub-edge region is connected in sequence along the direction close to the first middle region until it is connected to the first middle region; the second edge region is divided into several second sub-edge regions, and each second sub-edge region is connected in sequence along the direction close to the first middle region until it is connected to the first middle region. The process of first treating the surfaces located in the first and second edge regions using a focused ion beam includes the following steps: The surfaces located in several first sub-edge regions and several second sub-edge regions are treated using a focused ion beam. The processing order is as follows: first, the surfaces located in the first sub-edge regions and the second sub-edge regions located far from the first central region are treated, and then the surfaces located in the first sub-edge regions and the second sub-edge regions located close to the first central region are treated.

3. The method for preparing transmission electron microscopy samples using a focused ion beam according to claim 1, characterized in that, The third side region is divided into several third sub-side regions, and each third sub-side region is connected in sequence along the direction close to the second central region until it is connected to the second central region; the fourth side region is divided into several fourth sub-side regions, and each fourth sub-side region is connected in sequence along the direction close to the second central region until it is connected to the second central region. The process of pre-treating the surfaces located in the third and fourth edge regions using a focused ion beam includes the following steps: The surfaces located in several third sub-side regions and several fourth sub-side regions are treated using a focused ion beam. The processing order is as follows: first, the surfaces located in the third sub-side regions and the fourth sub-side regions that are far from the second central region are treated, and then the surfaces located in the third sub-side regions and the fourth sub-side regions that are close to the second central region are treated.

4. The method for preparing transmission electron microscopy samples using a focused ion beam according to claim 1, characterized in that, The parameters for treating the surfaces located in the first edge region, first middle region, second edge region, third edge region, second middle region, and fourth edge region using focused ion beam treatment each independently include one or more of the following parameters: a) The ion beam voltage is 2 kV~10 kV; b) Ion beam current is 10 pA to 40 pA; c) Bombard the surface to be treated with an ion beam at an incident angle of 82° to 88°.

5. The method for preparing transmission electron microscopy samples using a focused ion beam according to claim 1, characterized in that, The first side is perpendicularly connected to the second side.

6. The method for preparing transmission electron microscopy samples using a focused ion beam according to claim 1, characterized in that, The cutting process satisfies the following condition: the cutting zone formed by the cutting process can accommodate the sample precursor.

7. The method for preparing transmission electron microscopy samples using a focused ion beam according to claim 1, characterized in that, The first surface further includes a first end region located at an end away from the first side or the second side and connected to the first observation area. The second surface further includes a second end region located at an end away from the first side or the second side and connected to the second observation area. The first end region and the second end region correspond to each other. In the transmission electron microscope sample, the distance between the surface located in the first end region and the surface located in the second end region is greater than the distance between the surface located in the first observation region and the surface located in the second observation region.

8. The method for preparing transmission electron microscopy samples using a focused ion beam according to any one of claims 1 to 7, characterized in that, The thickness reduction achieved by treating the first surface with a focused ion beam is 20% to 30% of the thickness of the sample precursor before the current treatment. The thickness reduction achieved by treating the second surface with a focused ion beam is 20% to 30% of the thickness of the sample precursor before the current treatment.

9. The method for preparing transmission electron microscopy samples using a focused ion beam according to claim 8, characterized in that, The parameters for treating the first and second surfaces using a focused ion beam each independently include one or more of the following parameters: a) The ion beam voltage is 15 kV~30 kV; b) The ion beam current is 45 pA to 1.5 nA; c) Bombard the first surface with an ion beam at an incident angle of 88.5° to 89.5° or bombard the second surface with an ion beam at an incident angle of 88.5° to 89.5°.

10. The method for preparing transmission electron microscopy samples using a focused ion beam according to any one of claims 1 to 7, 9, characterized in that, The extraction of sample precursors from the test region of the analyte using a focused ion beam includes the following steps: The area to be tested is determined, and a protective layer is formed on the area to be tested; Retain the connection between a portion of the material in the area to be tested and the material in the surrounding area, and sever the connection between the remaining side and the material in the surrounding area. The extraction device is fixed to the side of the substance in the area to be tested that is away from the retention side. The connection between the remaining side of the substance in the test area and the substance in the surrounding area is severed, and the connection between the bottom of the substance in the test area and the substance in the surrounding area is severed to obtain the sample precursor.

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