A micro-particle whole section FIB-TKD processing characterization method

Abstract

The application provides a kind of micro-particle whole section FIB-TKD processing characterization method, comprising the following steps: 1. sample preparation: load powder particles on the cut copper foil section, the copper foil is ten microns to several tens of microns thick, clamp the copper foil on the sample holder, the edge is exposed 1-3mm, put into double-beam electron microscope, deposit a protective layer on the upper surface of powder particles, and then perform enhanced deposition on both sides of powder particles. 2. Thinning: use TEM sample preparation program to thin the particles. 3. TKD characterization: make the thin area of powder particles 20° with the horizontal plane, insert the electron backscatter diffraction (EBSD) detector, and perform TKD characterization. The application integrates FIB preparation and TKD characterization by optimizing the process, strengthens the fixation, enhances the conductivity of the deposition layer, improves the deposition efficiency, and can prepare the whole particle section and successfully characterize.

Description

Technical Field

[0001] This invention relates to the field of material microstructure characterization technology, and in particular to a FIB-TKD processing characterization method for the entire cross-section of micron-sized particles, which is used to achieve high-resolution analysis of the crystal orientation and interface structure inside the entire cross-section of micron-sized powder particles. Background Technology

[0002] Micrometer-sized particles (ranging from hundreds of nanometers to tens of micrometers) are widely present in various material systems. Their internal microstructure, such as crystal orientation, phase distribution, and grain boundary characteristics, directly affects the macroscopic properties of the materials. Accurate characterization of the crystallographic information of micrometer particles is of great scientific significance and application value for understanding the formation mechanism of materials, optimizing preparation processes, and predicting performance.

[0003] Traditional micron-sized particle characterization techniques primarily rely on scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM can rapidly acquire information on the surface morphology and composition of particles, but it cannot deeply analyze the internal crystal structure. Although TEM has atomic-level resolution, the sample preparation process is complex. Micron-sized particles are easily lost, broken, or structurally altered during sample preparation steps such as grinding and ion thinning. Furthermore, the field of view for a single analysis is extremely small, making it difficult to obtain statistical information about the overall particle structure.

[0004] The advent of electron backscatter diffraction (EBSD) has made it possible to perform crystallographic characterization in SEM. By collecting the Kikuchi pattern formed by backscattered electrons, information such as the crystal orientation, phase composition, and grain boundary type of the sample can be obtained. However, EBSD technology has the following limitations:

[0005] (1) The spatial resolution is usually 20-100 nanometers. Due to the interaction volume of backscattered electrons, it is difficult to distinguish nanoscale grains and substructures. However, micron-sized particles often have grains ranging from a few nanometers to tens of nanometers, which may lead to poor calibration when characterizing micron-sized particles.

[0006] (2) The sample surface is required to be flat and free of damage layer. Fine mechanical polishing and electrolytic polishing are required. For multiphase materials and tiny particles with large hardness differences, surface preparation is extremely difficult.

[0007] EBSD systems are typically mounted as accessories on SEMs or dual-beam electron microscopes, enabling both traditional EBSD analysis and transmission Kikuchi diffraction (TKD) tests in transmission mode. In recent years, the developed transmission Kikuchi diffraction (TKD), also known as transmission-EBSD (t-EBSD), improves spatial resolution by collecting Kikuchi patterns formed by transmitted electrons passing through thin samples, providing a new approach for nanoscale crystallographic characterization. It is particularly suitable for characterizing micron-sized particles with grain sizes ranging from a few nanometers to tens of nanometers. However, TKD requires sample thicknesses less than 100 nanometers, posing a significant challenge to the preparation of micron-sized particles. Dual-beam FIB-SEM systems integrate focused ion beams and scanning electron beams in the same device, enabling simultaneous processing and observation, providing the hardware foundation for in-situ integrated analysis. Focused ion beam (FIB) technology utilizes a high-energy ion beam (typically gallium ions, Ga)... + FIB (Fiber Embedded Injection) technology enables nanoscale precision material etching, deposition, and imaging, and has been widely applied in cross-sectional sample preparation, 3D tomography, and TEM sample preparation. FIB can precisely control the cutting depth and position, processing micron-sized particles into ultrathin samples that meet TKD (Total Knockout Diagnosis) requirements. However, the traditional FIB-TKD analysis process requires the following steps:

[0008] (1) Using the process of preparing TEM samples, the particles were located and processed in the FIB equipment.

[0009] (2) Remove the processed sample from the vacuum chamber and load it onto the TKD special sample holder.

[0010] (3) Transfer to a SEM or dual-beam electron microscope equipped with a TKD detector.

[0011] (4) Re-vacuum, position the sample and perform TKD collection.

[0012] This process presents numerous problems: it is cumbersome and time-consuming (usually taking several hours); samples are exposed to the atmospheric environment during transfer, increasing the risk of surface oxidation and contaminant adsorption; and mechanical clamping and transfer can damage thin samples. These issues severely impact analytical efficiency and result reliability.

[0013] If the entire process from particle processing to TKD characterization could be completed directly in FIB-SEM, it would greatly improve analytical efficiency, avoid sample contamination and damage, and reduce operational complexity. However, there is currently a lack of systematic FIB-TKD in-situ processing and characterization methods for micron-sized particles, including key technical aspects such as particle fixation and positioning, ultrathin sample preparation strategies, and the FIB preparation-TKD acquisition process.

[0014] It is also important to note that characterizing a complete cross-section of a particle has irreplaceable advantages over partial cross-sections: it can reveal the complete characteristics of grain boundaries, accurately calculate the true proportions of each phase component, and identify long-range defects such as cracks or pores penetrating the particle—information that cannot be obtained through local scanning. However, preparing and characterizing complete particles not only involves a large processing area but also requires consideration of the extremely small contact area between the nearly spherical micron-sized particles and the matrix. This presents significant technical challenges during FIB thinning and TKD characterization of the entire particle. On the one hand, firmly fixing the particles is difficult, and the small contact area leads to insufficient mechanical bonding, making them prone to displacement or detachment under prolonged FIB ion beam bombardment. On the other hand, TKD characterization typically uses high accelerating voltages (e.g., 20-30 kV) and high beam currents (nA level) to bombard the sample. If the fixation between the particles and the matrix is ​​not firm enough or the conductive path is obstructed, charge accumulation can lead to sample drift, image distortion, or even a severe deterioration in Kikuchi pattern quality, greatly affecting the accuracy and reliability of crystallographic characterization.

[0015] Therefore, achieving robust fixation and good conductive connection of micron-sized particles is a key prerequisite for successful whole-particle FIB-TKD characterization. Thus, there is an urgent need to develop an in-situ processing and characterization method based on FIB-TKD for intact cross-sections of micron-sized particles, enabling precise thinning and high-resolution crystallographic analysis of intact particles in a single instrument (a dual-beam electron microscope equipped with EBSD), to meet the pressing needs of materials science, nanotechnology, and other fields for characterizing the microstructure of micron-sized particles.

[0016] The technical solution of existing technology 1: A sample holder and scanning electron microscope inspection system for FIB-TKD combined use are disclosed in this application. The sample holder can be used to adjust the position of the sample to quickly and efficiently prepare a planar transmission electron microscope sample that meets the test requirements, and can also complete transmission EBSD (TKD) experiments.

[0017] Disadvantages of existing technology 1: The device used in this invention is relatively complex and requires the use of an extraction method. The described "sample preparation system includes a FIB sample preparation unit, a product extraction unit, a sample welding unit, and a sample thinning unit; the FIB sample preparation unit extracts a thin sheet sample from the original sample; the sample extraction unit transfers the thin sheet sample to a semi-copper mesh on a sample holder; the sample welding unit welds and fixes the thin sheet sample and the semi-copper mesh; the sample thinning unit reduces the thickness of the thin sheet sample." The sample extraction unit uses a robotic arm to extract and transfer the sample.

[0018] Extracting and placing the sample on a copper mesh is a common step in TEM sample preparation, but it is time-consuming. If a localization operation is performed, i.e., extracting the sample from a feature point for thinning, the extraction step is essential. However, if localization is not required, the extraction step introduces additional complexity and time consumption. For example, in characterizing micron-sized particles, it is sufficient to select one from a large pool of particles; specific localization and extraction are unnecessary.

[0019] Furthermore, the component includes a copper mesh clamp, which still employs the method for preparing TEM samples to prepare TKD samples. Because TEM and FIB cannot be used on the same equipment, and the TEM fixture needs to hold a 3mm sample, FIB preparation of TEM samples requires the use of a semi-copper mesh. A pre-thinned portion is extracted from the sample and soldered onto the semi-copper mesh. However, TKD can be used on the same equipment as FIB, and TKD samples do not necessarily need to be placed on a semi-copper mesh.

[0020] Furthermore, this invention is only a general method and cannot be directly used for FIB processing of TKD samples with an overall cross-section of micron-sized particles.

[0021] Technical solution of existing technology 2: An in-situ electrochemical transmission Kikuchi diffraction testing device and method for cathode materials is disclosed. This invention can be used in various types of scanning electron microscopes to characterize cathode particles by transmission Kikuchi diffraction under in-situ electrochemical loading, obtaining information such as the orientation, shape, and size of grains at different potential states, thus providing support for the development of cathode materials.

[0022] Disadvantages of existing technology 2: A focused ion beam is used to cut away the portion of the positive electrode particle not covered by the protective layer from the top, forming a thin positive electrode sheet for the battery under test. This sheet is then separated from the silicon substrate and lifted out by a robotic arm. This technique, like existing technology one, requires an extraction operation.

[0023] In steps 1-3 of this method, the protective layer has a width of 2 μm and a length equal to the diameter of the positive electrode particle plus 2 μm on each side, uniformly coating the surface of the positive electrode particle. However, the deposition method and process are not specified. According to known methods, electron beam deposition followed by ion beam deposition is used, and the beam current for ion beam deposition cannot be too high (tens to hundreds of pA), otherwise it will damage the particles. Although the deposition time is not mentioned, this deposition method is extremely time-consuming.

[0024] In addition, this method requires digging a pit at the bottom of the particle and the bottom of the copper pillar, which will result in an incomplete cross-section of the particle.

[0025] Existing technology three: A non-targeted, extraction-free integrated method for FIB preparation and TKD characterization is disclosed. This method includes: fixing the pretreated sample and placing it in a dual-beam electron microscope (FIB-SEM) to select the processing area; performing FIB processing, first depositing a protective layer in the processing area of ​​the sample, then using an ion beam to thin the top and bottom of the sample until it is transparent to the electron beam; then using an ion beam to clean the sample to reduce the amorphous layer; and finally performing TKD characterization. This method primarily addresses the problems of existing techniques where sample transfer from FIB preparation to a copper mesh is cumbersome, prone to sample damage, and inefficient in the FIB-TKD process. Combining FIB and TKD saves extraction time, simplifies the steps, improves efficiency, reduces limitations on sample size, allows for remediation of defects, and is applicable to bulk materials, thin films, and particles processed in non-targeted locations.

[0026] The disadvantages of existing technology three: This method can process micron-sized particles, but it's a technical approach without optimization for micron-sized particles. In practice, it faces difficulties similar to existing technology two: depositing a protective layer on the particle surface, with a width of 1-2 μm and a length equal to the diameter of the positive electrode particle plus 2 μm on each side, and uniformly covering the particle surface, is time-consuming. Furthermore, improper process control can lead to incomplete deposition or damage to the particle sample. In the IBID process, ion beam etching and deposition effects coexist, with deposition dominating under normal conditions. The nanoscale protrusions commonly found on the surface of micron-sized particles easily cause process runaway—the protrusions become preferential etching points, easily suffering irreversible morphological and structural damage under standard beam current. To avoid this damage, the ion beam current sometimes has to be reduced to below 20 pA, but at the cost of a significant decrease in deposition efficiency. If the protective layer is incomplete, especially if the needle in the gas injection system is on one side of the particle, the deposition efficiency on the side away from the needle will be low. This results in the inability to process and characterize the entire particle cross-section; only a portion of the cross-section can be processed, with the rest serving a supporting role. If FIB thinning is performed on the entire cross-section of particles with poor deposition and weak foundation, it often leads to poor cross-sectional contact, making them prone to collapse or drift during characterization. Therefore, a more comprehensive solution and a more time-saving and robust method are needed to process the entire cross-section of the particles. Summary of the Invention

[0027] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a FIB-TKD processing characterization method for the overall cross-section of micron-sized particles.

[0028] This invention, based on fundamental principles, directly processes particles without referencing standard extraction processes for preparing transmission samples. However, the particles are very small, so they are attached to the tip of a thin sheet, which is readily available, such as copper or aluminum foil (typically about 20 micrometers thick). The particle surface requires a protective layer, and the sides need support. Simple EBID and IBID are very time-consuming and may result in poor deposition. Therefore, IBID combined with a redeposition effect is used on both sides, employing a larger beam current to improve deposition efficiency and effectiveness. Thinning is then performed until the electron beam is transparent, borrowing thinning and cleaning techniques from transmission samples. It is also important to note that conventional deposition using EBID and IBID processes results in a protective layer with high resistivity (using platinum as an example) because it contains many organic components, and the platinum particles exist in an extremely small nanocrystalline state. Using this invention, the conductivity is significantly increased due to the presence of redeposited copper or aluminum within the deposit.

[0029] The present invention adopts the following technical solution: A method for characterizing the integral cross-section of micron-sized particles using FIB-TKD processing, including... Step 1. Sample preparation: The powder particles are loaded onto the cut copper foil cross-section, the copper foil being 10 to tens of micrometers thick. The copper foil is then clamped onto the sample holder, with the edges exposed by 1-3 millimeters. The sample is placed in a dual-beam electron microscope, and a protective layer is deposited on the surface of the powder particles. Then, the deposition is enhanced on the sides of the powder particles.

[0030] Step 2. Thinning: Thin the particles using the TEM sample preparation procedure.

[0031] Step 3. TKD characterization: Rotate the electron microscope sample stage by 70° so that the horizontal plane of the thin particle region is at 20°, insert the electron backscatter diffraction (EBSD) detector, and perform TKD characterization.

[0032] Furthermore, in step 1, the powder particles are loaded onto the copper foil cross-section in three ways: Method 1: Dip a toothpick soaked in anhydrous ethanol into the powder and touch the tip of the toothpick to the copper foil cross-section; Method 2: Add anhydrous ethanol to the powder, disperse it by ultrasonication to obtain a dispersion of appropriate concentration, and use a dropper to add the dispersion to the copper foil cross-section; Method 3: Immerse the copper foil in the dispersion.

[0033] Furthermore, the deposition of a protective layer on the surface of the powder particles includes: depositing a protective layer on the powder particles using EBID and IBID processes. In the EBID process, the electron beam voltage is 1kV, the current is 3nA, and the deposition thickness is 100nm. In the IBID process, the ion beam voltage is 30kV, the current is 100pA, and the deposition thickness is 2μm.

[0034] Furthermore, the particle-side enhanced deposition includes: setting processing regions at approximately several hundred nanometers (200-500 nm) on both sides of the powder particles, and performing deposition using an ion beam current higher than that of conventional IBID. The process employs an oblique incidence of the ion beam, allowing it to act simultaneously on the particle sides and the adjacent copper substrate. Copper atoms generated from sputtering the copper substrate, along with the decomposition of the precursor gas, jointly achieve composite deposition on the particle sides, improving the conductivity and density of the protective layer.

[0035] Furthermore, in enhanced deposition, the ion beam current is 1.5 nA or higher.

[0036] Step 2 includes: gradually reducing the beam current, thinning the powder particles sequentially from top to bottom, with the aid of a small tilt angle (0.5°-1.5°), an accelerating voltage of 30kV for the FIB, and a beam current selection range of 50pA-3nA. When the electron beam becomes transparent, the total thickness of the film is 100nm, and the thickness of the amorphous layer is approximately 30nm. The thickness of the amorphous layer is then further reduced using a low-voltage ion beam, with an accelerating voltage of 5kV and a beam current of 10pA for the FIB. Finally, the thickness of the amorphous layer in the thin region is less than 10nm.

[0037] During the thinning process in step 2, the supports on both sides of the powder particles need to maintain a thickness of several hundred nanometers.

[0038] The beneficial effects of this invention are: Firstly, it eliminates the need for extraction, integrating processes and reducing steps, simplifying the workflow, saving time, and increasing the success rate. Secondly, it enhances deposition: the process of combining redeposition with conventional IBID is called enhanced deposition. If the particle sides are not deposited, the particles lack support during thinning, or only a portion of the particle cross-section can be processed. To process and characterize the entire cross-section, the sides and bottom need support. However, for particle side deposition, the conventional EBID plus IBID process is time-consuming, and improper processing can damage the particles (e.g., excessive ion beam current can easily erode the particle edges), and the density and filling of the spherical particle-matrix interface are relatively poor. More importantly, the conductivity of the deposited products is not particularly good (for example, the resistivity of platinum deposited products is one to two orders of magnitude higher than that of pure platinum), and the thermal conductivity is also poor. During TKD characterization, the electron beam voltage and current are very high, which may cause sample drift. Using enhanced deposition, which introduces redeposition to deposit side support, the filling is better, the efficiency is higher, and the time is shorter. For example, conventional IBID can only use relatively low beam currents (e.g., 100 pA), which can easily erode the particles if not handled carefully. However, enhanced deposition uses higher beam currents (e.g., 1.5 or 3 nA) because it does not deposit directly on the particles, so the high beam current will not damage them. Furthermore, redeposition introduces copper components into the substrate, which has better electrical and thermal conductivity than the aforementioned platinum deposits. Thus, the new process provides better side and bottom support, resulting in better deposition effects, higher efficiency, and improved electrical and thermal conductivity, effectively ensuring the success of subsequent ion beam thinning and TKD characterization. Attached Figure Description

[0039] Figure 1 This is a flowchart of the steps of the present invention.

[0040] Figure 2 This is a cross-sectional view of the micron-sized particles of the present invention.

[0041] Figure 3 This is a schematic diagram of the overall process of the present invention, showing sample placement: (a) sample preparation, (b) ordinary FIB deposition, (c) enhanced FIB deposition, (d) FIB thinning, and (e) TKD characterization.

[0042] Figure 4 This is a schematic diagram of the placement of ordinary deposition and enhanced deposition according to the present invention.

[0043] Figure 5 The following are examples of the placement of ordinary and enhanced sedimentation according to the present invention. (a) is ordinary sedimentation, and (b) is enhanced sedimentation (the GIS needle was withdrawn for clarity of the image; it should actually be inserted during actual operation).

[0044] Figure 6 The diagram shows the positions during FIB thinning and TKD characterization: (a) FIB thinning, (b) TKD characterization.

[0045] Figure 7 A schematic diagram illustrating the principle of enhancing the deposition process.

[0046] Figure 8 A schematic diagram to enhance the post-deposition effect.

[0047] Figure 9 The diagrams for the deposition protective layer in the implementation case are as follows: (a) is the initial situation, (b) is the deposition protective layer above the particles, and (c) is the effect after enhanced deposition.

[0048] Figure 10 This is a scanning electron microscope (SEM) image showing the thinning process after the protective layer has been deposited in the implementation case.

[0049] Figure 11 This is a scanning electron microscope image taken after the thinning process in the implementation case, in preparation for TKD characterization.

[0050] Figure 12 This is the orientation diagram after TKD characterization in the implementation case.

[0051] Figure 13 The copper distribution diagram of the protective layer in the implementation case shows the copper element enriched on the side. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0053] In ion beam processing (such as FIB / SEM), "redeposition" or "re-deposition" refers to the phenomenon where material, after being removed or sputtered, returns in particle / atomic form and "re-deposits" in the surrounding area. More specifically, it means that material particles sputtered / stripped by the ion beam are not completely removed by the vacuum system but instead redeposit into adjacent areas or sidewalls, forming unintended thin layers or deposits. This is often a harmful phenomenon.

[0054] This invention targets micron-sized particle samples with fine crystal structures, integrating FIB preparation and TKD characterization through process optimization. Simultaneously, it strengthens fixation, enhances the conductivity of the particle's side support structure, improves deposition efficiency, and allows for the preparation and successful characterization of the entire particle cross-section. While possessing these advantages, it also significantly improves the efficiency and success rate of preparation and characterization, making it the most time-saving solution.

[0055] The expected cross-section of the processed particles is as follows Figure 2 As shown, the particles on the copper or aluminum substrate are covered by a protective layer deposited using conventional processes (EBID and IBID). The particles are supported on both sides, and the structures on both sides are mainly prepared by enhanced deposition (redeposition and IBID) processes.

[0056] like Figures 1-13 As shown, the FIB-TKD processing characterization method for the integral cross-section of micron-sized particles according to the present invention includes the following steps: Sample preparation: Cut copper foil (tens of micrometers to tens of micrometers thick) beforehand. Dip a toothpick moistened with anhydrous ethanol into powder, then touch the tip of the toothpick to the cross-section of the copper foil. Alternatively, add the powder to anhydrous ethanol, disperse it ultrasonically to obtain a dispersion of appropriate concentration, and then use a dropper to add the dispersion to the cross-section of the copper foil, or immerse the copper foil in the dispersion. After these operations, powder particles will remain on the cross-section (matrix) of the copper foil. After the sample is prepared, clamp the copper foil on a sample holder, with 1-3 mm of the edge exposed, and then place it in a dual-beam electron microscope.

[0057] Depositing a protective layer on the particle surface: The protective layer was deposited on the particle using EBID and IBID processes in sequence. The EBID process used an electron beam voltage of 1KV and a current of 3nA, with a deposition thickness of about 100nm. The IBID process used an ion beam voltage of 30KV and a current of 100pA, with a deposition thickness of about 2μm.

[0058] Enhanced deposition is performed on the particle sides: the purpose is to deposit side support. The angle between the ion beam and the sample differs from the previous step, and the deposition process also differs. The ion beam does not act directly on the particle, but rather obliquely incident on the substrate next to the particle. The sputtered copper particles are then deposited on the side of the particle, and IBID is also deposited simultaneously. This two-stage deposition process increases deposition efficiency and provides good coverage. This process is required on both sides of the particle, so after one side is processed, the sample needs to be rotated 180° and the same operation is performed on the other side. Specifically, a processing area of ​​approximately several hundred nanometers (200-500 nm) is set on both sides of the powder particles, and deposition is performed using an ion beam current higher than that of conventional IBID. The process employs an oblique incidence of the ion beam, allowing it to act simultaneously on the particle sides and the adjacent copper substrate. The copper atoms generated by sputtering the copper substrate and the precursor gas decomposition jointly achieve composite deposition on the particle sides, improving the conductivity and density of the protective layer. During enhanced deposition, the ion beam current is 1.5 nA or higher.

[0059] Thinning: The particles were precisely thinned using common TEM sample preparation procedures: the beam current was gradually reduced, and the particles were thinned sequentially from top to bottom, aided by a small tilt angle (approximately ±1.5°; for example, when thinning the top, the angle between the ion beam and the top surface was adjusted to 1.5°, and when thinning the bottom of the etched sample, the angle was adjusted to -1.5°). The FIB accelerating voltage was 30 kV, and the beam current selection range was 50 pA-3 nA. When the electron beam became transparent, the total film thickness was approximately 100 nm. Based on empirical rules, the amorphous layer thickness at this point was approximately 30 nm (the surface of the film etched by the ion beam becomes amorphous, and the thickness of the amorphous layer is positively correlated with the ion beam accelerating voltage). The thickness of the amorphous layer was further reduced using a low-voltage ion beam, with an FIB accelerating voltage of 5 kV and a beam current of 10 pA. Finally, the amorphous layer in the thin region was relatively thin (less than 10 nm). When thinning, care should be taken not to thin the supports on both sides of the particle too much, that is, thicker than the thin area, maintaining a thickness of several hundred nanometers, so that it can serve both as a support and as a conductor.

[0060] TKD characterization: The electron microscope stage is rotated 70° so that the horizontal plane of the thin particle region is at 20° (this is the most commonly used TKD characterization angle), and an electron backscatter diffraction (EBSD) detector is inserted to perform TKD characterization.

[0061] Example In this embodiment, the FIB-TKD processing characterization method based on the enhanced deposition effect of micron-sized particles is used to study LiNi. 0.6 Mn 0.4O2 The crystallographic characteristics of the cathode material particles (abbreviated as NM64) were determined using a Zeiss Crossbeam 350 dual-beam electron microscope, following these steps: Step 1: Sample Preparation (1) Disperse NM64 powder particles and load them onto a pre-cut copper foil cross-section, the copper foil being approximately 20 μm thick. During dispersion, use a toothpick moistened with anhydrous ethanol to pick up the powder and touch the tip of the powder-coated toothpick to the copper foil cross-section.

[0062] (2) Clamp the copper foil on the sample holder, so that its edge protrudes about 1-3 mm, and ensure that the particles are located at the free end of the copper foil.

[0063] (3) Place the sample holder into the sample chamber of the dual-beam electron microscope.

[0064] (4) Select the target NM64 particles and observe their morphology under scanning electron microscopy to determine the particles to be processed. A schematic diagram of this step is shown below. Figure 3 (a) See example diagram below. Figure 9 (a)

[0065] (5) A platinum protective layer is deposited on the surface of the particles sequentially using electron beam induced deposition and ion beam induced deposition. During electron beam induced deposition, the sample stage is placed horizontally, and the electron beam is directed towards the sample surface for deposition. During ion beam induced deposition, the sample stage is tilted at 54°, and the ion beam is directed towards the sample surface to continue deposition on top of the electron beam deposited layer. The expected thickness is approximately 1-2 μm, covering the surface of the area to be processed. A schematic diagram of this step is shown below. Figure 3 (b) See the location diagram in the middle. Figure 4 (a) See the actual image taken under an electron microscope. Figure 5 (a) See example diagram below. Figure 9 (b)

[0066] (6) Enhanced deposition is achieved at the edges of both sides of the particle using ion beam-induced deposition combined with redeposition. When depositing one side, the sample stage is placed horizontally and then rotated 90° so that the ion beam is angled towards the area near the bottom of the particle. When depositing the other side, it is rotated 180° so that the ion beam is angled towards the area near the bottom of the other side of the particle. At this time, the gas injection system is turned on, and a larger beam current (e.g., 30 kV, 1.5 nA or 3 nA) is used, so that ion beam-induced deposition and etching occur simultaneously in the target area. Ion beam-induced deposition deposits platinum and carbon, while etching sputters copper near the particle, as well as some of the deposited platinum and carbon, but some of the sputtered components are redeposited onto the sides of the particle (see schematic diagram). Figure 7 After enhanced deposition, not only does ion beam-induced deposition increase the support on both sides and fill the gaps between particles and the substrate, but the resputtering process also causes the copper foil substrate material (copper) to be sputtered and redeposited into the protective layer, forming a copper-containing enhanced deposition layer (see schematic diagram). Figure 8 The thickness of this deposited layer is approximately 1-2 μm. The presence of copper improves the conductivity of the deposited layer, and the increased deposition efficiency allows the deposited layer to provide sufficient mechanical support. See the schematic diagram of the placement of this step. Figure 3 (b) See the more precise location map in the middle. Figure 4 (b) See the actual image taken under an electron microscope. Figure 5 (b), see example diagram. Figure 9 (c)

[0067] Step 2: Thinning treatment (7) Precise thinning of particles was performed using a transmission sample preparation procedure: a focused ion beam was used to progressively mill the particles from both sides, with the beam current decreasing stepwise (from 30kV / 7nA → 30kV / 0.05nA), assisted by a small tilt angle (approximately ±1.5°; for example, when thinning the top, the angle between the ion beam and the top surface was adjusted to 1.5°, and when thinning the bottom of the etched sample, the angle was adjusted to -1.5°). The transparency of the thin area was monitored in real time during the thinning process to ensure that a thin area that the electron beam could pass through was obtained. After thinning, the target area was thinned to a thickness of less than 100nm.

[0068] (8) Use a low-energy ion beam (e.g., 5 kV, 10 pA) for final cleaning and polishing to remove surface damage layers and redeposited contaminants.

[0069] See the schematic diagram of the thinning process. Figure 3 (d) For a more precise location map, see [image 1] Figure 6 In Figure (a), an example of the thinning process is shown. Figure 10 See the image below for the finished product after thinning. Figure 11 .

[0070] Step 3: TKD characterization (9) Tilt the sample stage so that the thin area of ​​the particles is at an angle of about 20° to the horizontal plane so that the transmitted electrons can effectively excite the Kikuchi diffraction pattern; (10) Insert an electron backscatter diffraction (EBSD) detector; (11) Set scanning parameters: accelerating voltage 30kV, beam current about 1-10nA, step size 10-20 nm; (12) Perform TKD scanning to obtain crystallographic information such as crystal orientation distribution and grain boundary characteristics of thin regions of NM64 particles; (13) The collected data were processed using EBSD analysis software to generate orientation imaging diagrams (IPF diagrams), grain boundary distribution diagrams and pole diagrams, etc., and the microstructure characteristics of NM64 particles were analyzed.

[0071] A schematic diagram of TKD characterization is shown below. Figure 3 (e) See the more precise location map in the middle. Figure 6 In section (b), the results of instance characterization are shown in [reference]. Figure 12 .

[0072] Effect description This method successfully achieved high-resolution crystallographic characterization of the overall cross-section of micron-sized NM64 particles. Compared with traditional EBID / IBID deposition methods, the enhanced deposition layer formed by the redeposition effect exhibits higher conductivity (due to higher copper content, see...) Figure 13 The distribution of copper in the energy dispersive spectroscopy (EDS) effectively reduced the charging effect during the TKD test, improving the quality and calibration rate of Kikuchi flower samples (the calibration rate can reach over 85%). Simultaneously, the enhanced deposition layer provides better mechanical support, reducing the risk of sample deformation and damage during thinning. In contrast, the existing method only prepared a cross-section of about three-quarters of the particles, and the thin region drifted severely during characterization, resulting in a calibration rate of only about 65%. Furthermore, the thin region disappeared due to instability when adjusting parameters for recharacterization.

[0073] The entire sample preparation and characterization process is completed in situ in the same dual-beam electron microscope without the need for sample transfer. This avoids the problems of particle loss and structural changes in traditional TEM sample preparation, and achieves efficient and accurate characterization of micron-sized particle crystallographic information.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for characterizing the integral cross-section of micron-sized particles using FIB-TKD processing, characterized in that, include: Step 1. Sample preparation: Powder particles are loaded onto a cut copper foil cross-section, and then the copper foil is clamped on a sample holder. After being placed in a dual-beam electron microscope, a suitable powder particle is selected, and a protective layer is deposited on the surface of the particle. Then, an enhancement deposition process is performed on the sides of the powder particles. The enhancement deposition on the sides of the particles includes: setting up processing areas at a distance of 200-500 nm from the edge of the powder particle on both sides, using an ion beam current higher than the conventional IBID for deposition. During deposition, the ion beam current is 1.5 nA or higher, and the ion beam is obliquely incident so that it acts on the side of the particle and the adjacent copper substrate simultaneously. The copper atoms generated by sputtering the copper substrate and the precursor gas decomposition jointly achieve composite deposition on the side of the particle, improving the conductivity and density of the protective layer. Step 2. Thinning: Thin the particles using a TEM sample preparation procedure; Step 3. TKD characterization: Position the thin region of the powder particles at 20° to the horizontal plane, insert an electron backscatter diffraction (EBSD) detector, and perform TKD characterization.

2. The method according to claim 1, characterized in that, In step 1, when the copper foil is clamped on the sample holder, the edge of the copper foil should protrude 1-3 mm.

3. The method according to claim 1, characterized in that, In step 1, the powder particles are loaded onto the copper foil cross-section using any of three methods: Method 1: Dip a toothpick soaked in anhydrous ethanol into the powder and touch the tip of the toothpick to the copper foil cross-section; Method 2: Add anhydrous ethanol to the powder particles, disperse them ultrasonically to obtain a dispersion of appropriate concentration, and then use a dropper to add the dispersion to the copper foil cross-section; Method 3: Add anhydrous ethanol to the powder particles, disperse them ultrasonically to obtain a dispersion of appropriate concentration, and then immerse the copper foil in the dispersion.

4. The method according to claim 1, characterized in that, The deposition of a protective layer on the surface of powder particles includes: depositing a protective layer on top of powder particles using EBID and IBID processes.

5. The method according to claim 4, characterized in that, In the EBID process, the electron beam voltage is 1kV, the current is 3nA, and the deposition thickness is 100nm. In the IBID process, the ion beam voltage is 30kV, the current is 100pA, and the deposition thickness is 2μm.

6. The method according to claim 1, characterized in that, Step 2 includes: gradually reducing the beam current, thinning the powder particles sequentially from top to bottom, with the aid of a 0.5°-1.5° tilt, an accelerating voltage of 30kV for the FIB, a beam current selection range of 50pA-3nA, and thinning until the electron beam is transparent, at which point the total film thickness is 100nm, and the amorphous layer thickness is approximately 30nm. The thickness of the amorphous layer was further reduced using a low-voltage ion beam. The FIB acceleration voltage was 5kV and the beam current was 10pA. The final thickness of the amorphous layer in the thin region was less than 10nm.

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