Sample preparation method for molybdenum target EBSD detection

Abstract

The invention provides a sample preparation method for molybdenum target EBSD detection. The sample preparation method comprises the steps that a molybdenum target sample is sequentially subjected to grinding treatment, mechanical polishing treatment and electrolytic polishing treatment; the mechanical polishing treatment comprises first mechanical polishing, second mechanical polishing, third mechanical polishing and fourth mechanical polishing which are sequentially carried out; an electrolyte in the electrolytic polishing treatment is a mixed solution of methanol, ethylene glycol monobutyl ether and perchloric acid. The obtained EBSD sample is smooth and flat in surface and free of scratches, the diffraction Kikuchi zone of the sample is clear during EBSD detection, the analysis rate is high, and meanwhile the calibration rate of the sample is high.

Description

Technical Field

[0001] This invention belongs to the field of target material detection technology and relates to a sample preparation method for EBSD detection of molybdenum target material. Background Technology

[0002] Sputtering targets are key basic materials in the electronics and information industry, optical coating, and wear-resistant coating fields. Their working principle is based on magnetron sputtering: under the drive of an electric field, high-purity Ar... + Ions bombard the target surface, causing target atoms to escape and deposit on the substrate surface, forming a nanoscale functional thin film. Semiconductor-grade applications place three requirements on the target material: "extreme purity, extreme uniformity, and extreme stability." Among these, grain orientation, grain boundary characteristics, and texture uniformity directly determine the electrical, mechanical, and reliability indicators of the subsequent thin film.

[0003] To non-destructively and quantitatively characterize the three-dimensional crystallographic information of sputtering targets at the submicron scale, electron backscatter diffraction (EBSD) technology has been widely adopted in the industry. This technology integrates a high-sensitivity EBSD camera onto a scanning electron microscope (SEM) platform, combining the nanometer-scale spatial resolution of SEM with the crystallographic resolution of XRD. It can simultaneously map orientation differences and orientation relationships, orientation distribution functions, grain boundary types, and interface crystal indices of polycrystalline materials such as ceramics, semiconductors, superconductors, and metals. With its submicron-level spatial resolution and high-angle precision with a large field of view stitching capability, EBSD has become a core method for revealing the correlation between the "microstructure and macroscopic properties" of sputtering targets, providing a data loop for the preparation of highly consistent, long-life sputtering targets.

[0004] Molybdenum sputtering targets are metallic materials with molybdenum as the main component, possessing a high melting point, good electrical and thermal conductivity, and excellent mechanical properties. In EBSD testing, the surface quality of the molybdenum sputtering target has a crucial impact on the accuracy and reliability of the test results. Currently, EBSD sample preparation methods for molybdenum sputtering targets are not yet perfect, making it difficult to meet the EBSD technology's requirements for sample surface flatness, non-destructive properties, and high conductivity, thus limiting the acquisition of information such as orientation distribution.

[0005] Therefore, developing a molybdenum sputtering sample preparation method suitable for EBSD detection is of great significance for improving the quality and performance of molybdenum sputtering targets. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a sample preparation method for EBSD detection of molybdenum target materials. The resulting EBSD sample has a smooth and flat surface without scratches. During EBSD detection, the sample exhibits clear diffraction patterns with high resolution and a high sample calibration rate.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] This invention provides a sample preparation method for EBSD detection of molybdenum sputtering targets, the sample preparation method comprising:

[0009] The molybdenum target sample was subjected to grinding, mechanical polishing and electrolytic polishing in sequence.

[0010] The mechanical polishing process includes a first mechanical polishing, a second mechanical polishing, a third mechanical polishing, and a fourth mechanical polishing performed sequentially.

[0011] The electrolyte used in the electropolishing process is a mixture of methanol, ethylene glycol monobutyl ether, and perchloric acid.

[0012] In this invention, the polishing cloths used for the first, second, third, and fourth mechanical polishing processes are either velvet cloth or velvet-free cloth.

[0013] The sample preparation method provided by this invention involves sequentially grinding and multi-stage mechanical polishing of molybdenum target samples, followed by electrolytic polishing using an electrolytic polishing solution with specific components. This eliminates the need for corrosion treatment and allows for the mass production of EBSD samples that meet the requirements. Furthermore, the prepared EBSD samples exhibit high resolution.

[0014] It should be noted that a four-stage mechanical polishing process is used, with each stage employing finer abrasives to gradually reduce surface roughness, achieve a mirror finish, reduce surface micro-cracks and residual stress, avoid the risk of localized over-polishing, and facilitate subsequent electrolytic polishing operations.

[0015] It should also be noted that the electropolishing process specifically uses a mixture of methanol, ethylene glycol monobutyl ether and perchloric acid as the electrolyte, which can significantly improve the microscopic unevenness of the molybdenum target sample surface, making the surface smoother and more uniform, and enabling the sample to meet the EBSD test requirements.

[0016] Preferably, the grinding process includes a first grinding, a second grinding, a third grinding, and a fourth grinding performed sequentially.

[0017] In this invention, the device is rotated 90° after each grinding step to remove scratches from the previous grinding step. The grinding times for the first, second, third, and fourth grinding steps are all 4-10 minutes, for example, 4.5 minutes, 5 minutes, 5.5 minutes, 6 minutes, 6.5 minutes, 7 minutes, 7.5 minutes, 8 minutes, 8.5 minutes, 9 minutes, or 9.5 minutes.

[0018] Preferably, the grinding process is performed using SiC sandpaper.

[0019] Preferably, the first grinding uses sandpaper with a mesh size of 300#-500#, such as 320#, 340#, 350#, 360#, 380#, 400#, 420#, 440#, 450#, 460# or 480#, etc.

[0020] Preferably, the second grinding uses sandpaper with a mesh size of 700#-900#, such as 720#, 740#, 750#, 760#, 780#, 800#, 820#, 840#, 850#, 860# or 880#, etc.

[0021] Preferably, the third grinding process uses sandpaper with a mesh size of 1100#-1300#, such as 1120#, 1140#, 1150#, 1160#, 1180#, 1200#, 1220#, 1240#, 1250#, 1260# or 1280#, etc.

[0022] Preferably, the fourth grinding process uses sandpaper with a mesh size of 1800#-2200#, such as 1820#, 1850#, 1880#, 1900#, 1920#, 1950#, 1980#, 2000#, 2020#, 2050#, 2080#, 2100#, 2120#, 2150#, or 2180#, etc.

[0023] It should be noted that using sandpaper with gradually decreasing grit for four-stage grinding can gradually reduce and minimize scratches on the sample surface, thereby reducing the time required for subsequent mechanical polishing and electropolishing.

[0024] Preferably, the polishing fluid used in the first mechanical polishing includes a first diamond suspension.

[0025] Preferably, the diamond particle size in the first diamond suspension is 8μm-10μm, for example, it can be 8.2μm, 8.4μm, 8.5μm, 8.6μm, 8.8μm, 9μm, 9.2μm, 9.4μm, 9.5μm, 9.6μm or 9.8μm, etc.

[0026] Preferably, the time for the first mechanical polishing is 8 min to 12 min, for example, it can be 8.5 min, 9 min, 9.5 min, 10 min, 10.5 min, 11 min or 11.5 min, etc.

[0027] Preferably, the polishing fluid used in the second mechanical polishing includes a second diamond suspension.

[0028] Preferably, the diamond particle size in the second diamond suspension is 2μm-4μm, for example, it can be 2.2μm, 2.4μm, 2.5μm, 2.6μm, 2.8μm, 3μm, 3.2μm, 3.4μm, 3.5μm, 3.6μm or 3.8μm, etc.

[0029] Preferably, the second mechanical polishing time is 4 min to 6 min, for example, it can be 4.2 min, 4.5 min, 4.6 min, 4.8 min, 5 min, 5.2 min, 5.5 min, 5.6 min or 5.8 min, etc.

[0030] Preferably, the polishing fluid used in the third mechanical polishing includes a third diamond suspension.

[0031] Preferably, the diamond particle size in the third diamond suspension is 0.5μm-1.5μm, for example, it can be 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm or 1.4μm, etc.

[0032] Preferably, the time for the third mechanical polishing is 2 min to 4 min, for example, it can be 2.2 min, 2.5 min, 2.6 min, 2.8 min, 3 min, 3.2 min, 3.5 min, 3.6 min or 3.8 min, etc.

[0033] Preferably, the polishing fluid used in the fourth mechanical polishing includes a fourth diamond suspension.

[0034] Preferably, the diamond particle size in the fourth diamond suspension is 0.1μm-0.35μm, for example, it can be 0.12μm, 0.14μm, 0.15μm, 0.16μm, 0.18μm, 0.2μm, 0.22μm, 0.24μm, 0.25μm, 0.26μm, 0.28μm, 0.3μm, 0.32μm or 0.34μm, etc.

[0035] Preferably, the time for the fourth mechanical polishing is 2 min to 4 min, for example, it can be 2.2 min, 2.5 min, 2.6 min, 2.8 min, 3 min, 3.2 min, 3.5 min, 3.6 min or 3.8 min, etc.

[0036] It should be noted that by using abrasives with progressively decreasing particle size, and by controlling the abrasive particle size and time parameters for the first, second, third, and fourth mechanical polishing processes, residual stress can be reduced, the clarity of the Kikuchi band can be improved, and the surface roughness of the sample can be reduced, meeting the extremely high requirements of EBSD for flatness, while also providing an ideal surface for subsequent electropolishing.

[0037] Preferably, the volume ratio of methanol, ethylene glycol monobutyl ether, and perchloric acid is (70-80):(15-25):(5-7), for example, it can be 70:15:5, 72:18:5.5, 75:20:6, 78:23:6.5, or 80:25:7, etc.

[0038] Preferably, the mass concentration of the perchloric acid is 55%-65%, for example, it can be 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63% or 64%, etc.

[0039] Preferably, the temperature of the electropolishing treatment is -15℃ to -25℃, for example, it can be -16℃, -17℃, -18℃, -19℃, -20℃, -21℃, -22℃, -23℃ or -24℃, etc.

[0040] Preferably, the voltage of the electropolishing treatment is 23V-27V, for example, it can be 23.5V, 24V, 24.5V, 25V, 25.5V, 26V or 26.5V, etc.

[0041] Preferably, the current for the electropolishing process is 0.2A-0.4A, for example, it can be 0.22A, 0.24A, 0.25A, 0.26A, 0.28A, 0.3A, 0.32A, 0.34A, 0.35A, 0.36A or 0.38A, etc.

[0042] Preferably, the electropolishing treatment time is 10s-20s, for example, it can be 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s or 19s, etc.

[0043] It should be noted that by controlling the volume ratio of methanol, ethylene glycol monobutyl ether and perchloric acid, as well as the voltage and time in the electrolyte used for electropolishing, the smoothness of the sample surface can be further improved, the surface quality and purity can be enhanced, and the deformation stress layer after mechanical polishing of the sample can be eliminated to obtain molybdenum target EBSD samples.

[0044] Preferably, the sample preparation method further includes wire cutting of the molybdenum target sample before grinding.

[0045] In this invention, the preferred size of the molybdenum target sample after wire cutting is 15cm×15cm×10cm.

[0046] Preferably, the sample preparation method further includes cleaning and drying the molybdenum target sample sequentially after electrolytic polishing.

[0047] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) The sample preparation method provided by the present invention involves grinding and multi-stage mechanical polishing of the molybdenum target sample in sequence, followed by electrolytic polishing with an electrolytic polishing solution of specific components. No corrosion treatment is required. The molybdenum target sample can be mass-produced into EBSD samples that meet the requirements, and the prepared EBSD samples have a high resolution.

[0050] (2) The EBSD sample obtained by the sample preparation method provided by the present invention has a smooth and flat surface without scratches. When performing EBSD detection, the sample diffraction kiwi band is clear and has a high resolution and high stability. At the same time, the sample calibration rate is high, reaching more than 98%, and the results are accurate. Detailed Implementation

[0051] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0052] Example 1

[0053] This embodiment provides a sample preparation method for EBSD detection of molybdenum sputtering targets, the sample preparation method including:

[0054] (1) The molybdenum target sample was wire-cut to a size of 15cm×15cm×10cm, and then the first grinding, second grinding, third grinding and fourth grinding were performed in sequence. After each grinding, the sample was rotated 90° to remove the grinding scratches from the previous step. The grinding media used in the first grinding, second grinding, third grinding and fourth grinding were all SiC sandpaper, and the first EBSD test sample was obtained.

[0055] The grinding process involved four stages: the first grinding stage used 400# SiC sandpaper for 5 minutes; the second grinding stage used 800# SiC sandpaper for 5 minutes; the third grinding stage used 1200# SiC sandpaper for 5 minutes; and the fourth grinding stage used 2000# SiC sandpaper for 5 minutes.

[0056] (2) The first EBSD test sample was subjected to sequential mechanical polishing for 10 min, 5 min, 3 min, and 3 min, all on a lint-free polishing cloth. This yielded the second EBSD test sample.

[0057] The polishing slurry used in the first mechanical polishing includes a first diamond suspension with a diamond particle size of 9 μm; the polishing slurry used in the second mechanical polishing includes a second diamond suspension with a diamond particle size of 3 μm; the polishing slurry used in the third mechanical polishing includes a third diamond suspension with a diamond particle size of 1 μm; and the polishing slurry used in the fourth mechanical polishing includes a fourth diamond suspension with a diamond particle size of 0.25 μm.

[0058] (3) The second EBSD test sample was electropolished for 15s at a temperature of -20℃, a voltage of 25V and a current of 0.3A, and then cleaned and dried in sequence to obtain the EBSD test sample.

[0059] The electrolyte in the electropolishing process is a mixture of methanol, ethylene glycol monobutyl ether and perchloric acid in a volume ratio of 75:20:6, with a perchloric acid mass concentration of 60%.

[0060] Example 2

[0061] This embodiment provides a sample preparation method for EBSD detection of molybdenum sputtering targets, the sample preparation method including:

[0062] (1) The molybdenum target sample was wire-cut to a size of 15cm×15cm×10cm, and then the first grinding, second grinding, third grinding and fourth grinding were performed in sequence. After each grinding, the sample was rotated 90° to remove the grinding scratches from the previous step. The grinding media used in the first grinding, second grinding, third grinding and fourth grinding were all SiC sandpaper, and the first EBSD test sample was obtained.

[0063] The grinding process involved four stages: the first grinding stage used 300# SiC sandpaper for 6 minutes; the second grinding stage used 700# SiC sandpaper for 6 minutes; the third grinding stage used 1100# SiC sandpaper for 6 minutes; and the fourth grinding stage used 1800# SiC sandpaper for 6 minutes.

[0064] (2) The first EBSD test sample was subjected to sequential mechanical polishing for 8 minutes, 4 minutes, 2 minutes, and 2 minutes, all on a lint-free polishing cloth. This yielded the second EBSD test sample.

[0065] The polishing slurry used in the first mechanical polishing includes a first diamond suspension with a diamond particle size of 10 μm; the polishing slurry used in the second mechanical polishing includes a second diamond suspension with a diamond particle size of 4 μm; the polishing slurry used in the third mechanical polishing includes a third diamond suspension with a diamond particle size of 1.5 μm; and the polishing slurry used in the fourth mechanical polishing includes a fourth diamond suspension with a diamond particle size of 0.35 μm.

[0066] (3) The second EBSD test sample was electropolished for 20s at a temperature of -25℃, a voltage of 23V and a current of 0.2A, and then cleaned and dried to obtain the EBSD test sample.

[0067] In the electropolishing process, the electrolyte is a mixture of methanol, ethylene glycol monobutyl ether and perchloric acid in a volume ratio of 70:16:5, with a perchloric acid mass concentration of 62%.

[0068] Example 3

[0069] This embodiment provides a sample preparation method for EBSD detection of molybdenum sputtering targets, the sample preparation method including:

[0070] (1) The molybdenum target sample was wire-cut to a size of 15cm×15cm×10cm, and then the first grinding, second grinding, third grinding and fourth grinding were performed in sequence. After each grinding, the sample was rotated 90° to remove the grinding scratches from the previous step. The grinding media used in the first grinding, second grinding, third grinding and fourth grinding were all SiC sandpaper, and the first EBSD test sample was obtained.

[0071] The grinding process involved four stages: the first grinding stage used 500# SiC sandpaper for 4.5 minutes; the second grinding stage used 900# SiC sandpaper for 4.5 minutes; the third grinding stage used 1300# SiC sandpaper for 4.5 minutes; and the fourth grinding stage used 2200# SiC sandpaper for 4.5 minutes.

[0072] (2) The first EBSD test sample was subjected to sequential mechanical polishing for 12 min, 6 min, 4 min, and 4 min, all on a lint-free polishing cloth. This yielded the second EBSD test sample.

[0073] The polishing slurry used in the first mechanical polishing includes a first diamond suspension with a diamond particle size of 8 μm; the polishing slurry used in the second mechanical polishing includes a second diamond suspension with a diamond particle size of 2 μm; the polishing slurry used in the third mechanical polishing includes a third diamond suspension with a diamond particle size of 0.5 μm; and the polishing slurry used in the fourth mechanical polishing includes a fourth diamond suspension with a diamond particle size of 0.15 μm.

[0074] (3) The second EBSD test sample was electropolished for 10s at a temperature of -15℃, a voltage of 27V and a current of 0.4A, and then cleaned and dried in sequence to obtain the EBSD test sample.

[0075] The electrolyte in the electropolishing process is a mixture of methanol, ethylene glycol monobutyl ether and perchloric acid in a volume ratio of 80:24:7, with a perchloric acid mass concentration of 56%.

[0076] Example 4

[0077] This embodiment provides a sample preparation method for EBSD detection of molybdenum target material. Except for the fourth grinding step (1) where the SiC sandpaper has a mesh size of 1600#, all other conditions are the same as in Example 1.

[0078] Example 5

[0079] This embodiment provides a sample preparation method for EBSD detection of molybdenum target material. Except for the fourth grinding step (1) where the SiC sandpaper has a mesh size of 2400#, all other conditions are the same as in Example 1.

[0080] Example 6

[0081] This embodiment provides a sample preparation method for EBSD detection of molybdenum target material. Except for the absence of the fourth grinding in step (1), all other conditions are the same as in Example 1.

[0082] Example 7

[0083] This embodiment provides a sample preparation method for EBSD detection of molybdenum target material. Except for the diamond particle size of the first diamond suspension in step (2) being 6 μm, all other conditions are the same as in Example 1.

[0084] Example 8

[0085] This embodiment provides a sample preparation method for EBSD detection of molybdenum target material. Except for the diamond particle size of the first diamond suspension in step (2) being 12 μm, all other conditions are the same as in Example 1.

[0086] Example 9

[0087] This embodiment provides a sample preparation method for EBSD detection of molybdenum target material. Except for the diamond particle size of the fourth diamond suspension in step (2) being 0.45 μm, all other conditions are the same as in Example 1.

[0088] Example 10

[0089] This embodiment provides a sample preparation method for EBSD detection of molybdenum target material. Except for the current of 0.1A in the electrolytic polishing process in step (3), all other conditions are the same as in Example 1.

[0090] Example 11

[0091] This embodiment provides a sample preparation method for EBSD detection of molybdenum target material. Except for the current of 0.6A in the electrolytic polishing process in step (3), all other conditions are the same as in Example 1.

[0092] Example 12

[0093] This embodiment provides a sample preparation method for EBSD detection of molybdenum target material. Except for the electropolishing treatment time of 5s in step (3), all other conditions are the same as in embodiment 1.

[0094] Example 13

[0095] This embodiment provides a sample preparation method for EBSD detection of molybdenum target material. Except for the electropolishing treatment time of 30s in step (3), all other conditions are the same as in Example 1.

[0096] Comparative Example 1

[0097] This comparative example provides a sample preparation method for EBSD testing of molybdenum target material. Except for the absence of third mechanical polishing in step (2), all other conditions are the same as in Example 1.

[0098] Comparative Example 2

[0099] This comparative example provides a sample preparation method for EBSD testing of molybdenum sputtering targets. Except for the absence of the fourth mechanical polishing in step (2), all other conditions are the same as in Example 1.

[0100] Comparative Example 3

[0101] This comparative example provides a sample preparation method for EBSD detection of molybdenum target material. Except that the electrolyte in step (3) does not contain ethylene glycol monobutyl ether, all other conditions are the same as in Example 1.

[0102] The test samples prepared in the above embodiments and comparative examples were subjected to EBSD testing under the following conditions: magnification of 50X, scan step size of 8μm, working distance of 15-16mm, and working voltage of 30kV. The measured calibration rates are shown in Table 1.

[0103] Table 1

[0104] Calibration rate / % Example 1 98 Example 2 99 Example 3 98 Example 4 95 Example 5 96 Example 6 93 Example 7 91 Example 8 90 Example 9 92 Example 10 88 Example 11 89 Example 12 85 Example 13 92 Comparative Example 1 87 Comparative Example 2 88 Comparative Example 3 85

[0105] As shown in Table 1:

[0106] The sample preparation methods provided in Examples 1-3 of this invention employ a combination of grinding, mechanical polishing, and electrolytic polishing techniques, along with specific process steps and relevant parameter ranges. The resulting molybdenum target EBSD samples have smooth and flat surfaces without scratches, and the sample calibration rate is high, reaching over 98%.

[0107] A comparison of Examples 1 and 4-6 shows that if the grit of the sandpaper used for the fourth grinding is too low or if the fourth grinding is not performed, scratches remain on the sample surface, and subsequent polishing is difficult to completely remove them, resulting in blurred Kikuchi bands and reduced calibration rate. If the grit of the sandpaper used for the fourth grinding is too high, an extremely thin amorphous layer may be formed, affecting the EBSD image quality and reducing calibration rate.

[0108] A comparison of Examples 1 and 7-9 shows that if the abrasive particle size of the first mechanical polishing is too small, the stress layer cannot be completely removed, resulting in a decrease in the sample calibration rate; if the abrasive particle size of the first or fourth mechanical polishing is too large, a small amount of stress layer will also exist, both of which lead to a decrease in the sample calibration rate.

[0109] A comparison of Examples 1 and 10-13 shows that if the current or time of the electropolishing treatment is not within the preferred range, or if the polished surface of the sample to be tested has a large number of defects such as unevenness, corrosion pits and over-corrosion pits, or if the polished surface of the sample to be tested is dark and does not have a mirror-like metallic luster, or if the electropolishing efficiency is reduced, it is impossible to prepare an EBSD sample that meets the requirements, resulting in a low calibration rate of the prepared EBSD sample.

[0110] A comparison of Example 1 and Comparative Examples 1-2 shows that if the third or fourth mechanical polishing is not performed, the combined effect of the four levels of mechanical polishing cannot be utilized, resulting in the sample not being sufficiently polished and failing to provide a good surface for electrolytic polishing, thus leading to a decrease in the sample calibration rate.

[0111] A comparison of Example 1 and Comparative Example 3 shows that if the electrolyte does not contain ethylene glycol monobutyl ether, it cannot improve the polishing uniformity, thus failing to effectively improve the surface smoothness and also failing to synergistically exert the amorphous layer effect, resulting in a decrease in the sample calibration rate.

[0112] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A sample preparation method for EBSD detection of molybdenum sputtering targets, characterized in that, The sample preparation method includes: The molybdenum target sample was subjected to grinding, mechanical polishing and electrolytic polishing in sequence. The mechanical polishing process includes a first mechanical polishing, a second mechanical polishing, a third mechanical polishing, and a fourth mechanical polishing performed sequentially. The electrolyte used in the electropolishing process is a mixture of methanol, ethylene glycol monobutyl ether, and perchloric acid.

2. The sample preparation method according to claim 1, characterized in that, The grinding process includes a first grinding, a second grinding, a third grinding, and a fourth grinding performed sequentially; Preferably, the grinding process is performed using SiC sandpaper.

3. The sample preparation method according to claim 2, characterized in that, The first grinding process uses sandpaper with a mesh size of 300#-500#; Preferably, the second grinding uses sandpaper with a mesh size of 700#-900#; Preferably, the third grinding process uses sandpaper with a mesh size of 1100#-1300#; Preferably, the fourth grinding process uses sandpaper with a mesh size of 1800#-2200#.

4. The sample preparation method according to claim 1, characterized in that, The polishing fluid used in the first mechanical polishing includes a first diamond suspension; Preferably, the diamond particle size in the first diamond suspension is 8μm-10μm; Preferably, the time for the first mechanical polishing is 8-12 minutes.

5. The sample preparation method according to claim 1, characterized in that, The polishing fluid used in the second mechanical polishing includes a second diamond suspension; Preferably, the diamond particle size in the second diamond suspension is 2μm-4μm; Preferably, the second mechanical polishing time is 4-6 minutes.

6. The sample preparation method according to claim 1, characterized in that, The polishing fluid used in the third mechanical polishing includes a third diamond suspension; Preferably, the diamond particle size in the third diamond suspension is 0.5μm-1.5μm; Preferably, the third mechanical polishing time is 2-4 minutes.

7. The sample preparation method according to claim 1, characterized in that, The polishing fluid used in the fourth mechanical polishing includes a fourth diamond suspension; Preferably, the diamond particle size in the fourth diamond suspension is 0.1 μm-0.35 μm; Preferably, the fourth mechanical polishing time is 2-4 minutes.

8. The sample preparation method according to claim 1, characterized in that, The volume ratio of methanol, ethylene glycol monobutyl ether and perchloric acid is (70-80):(15-25):(5-7); Preferably, the mass concentration of the perchloric acid is 55%-65%.

9. The sample preparation method according to claim 1, characterized in that, The temperature for the electropolishing treatment is -15℃ to -25℃; Preferably, the voltage for the electropolishing treatment is 23V-27V; Preferably, the current for the electropolishing process is 0.2A-0.4A; Preferably, the electropolishing process takes 10-20 seconds.

10. The sample preparation method according to claim 1, characterized in that, The sample preparation method also includes wire cutting of the molybdenum target sample before grinding; Preferably, the sample preparation method further includes cleaning and drying the molybdenum target sample sequentially after electrolytic polishing.