A reference sample for calibration of scanning electron microscope and energy dispersive spectrometer and its preparation method

Abstract

This invention relates to a reference sample and its preparation method for scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) calibration, belonging to the technical field of SEM calibration reference sample preparation. The reference sample comprises a copper-aluminum connector, an inlay, and a surface carbon film. The copper-aluminum connector is equipped with SEM calibration markings and EDS peak position calibration markings. The SEM calibration markings include low-magnification, medium-magnification, and high-magnification markings, composed of orthogonal cross grids, and are located on the copper side of the copper-aluminum connector. The EDS peak position calibration markings include two marking lines parallel to the copper-aluminum interface, respectively located on both sides of the interface. This sample can be used for checking and calibrating multiple parameters of the SEM, such as magnification, image linearity distortion, EDS peak position, energy resolution, and high / low energy peak height ratio. The preparation method is simple, low-cost, and suitable for laboratory preparation. The reference sample is convenient and quick to use during the calibration process.

Description

Technical Field

[0001] This invention relates to a reference sample and its preparation method for calibration of scanning electron microscopes and energy dispersive spectrometers, specifically to a copper-aluminum sample and its preparation method for calibration of scanning electron microscopes and energy dispersive spectrometers, belonging to the technical field of scanning electron microscope calibration reference sample preparation. Background Technology

[0002] Scanning electron microscopes (SEMs) are important microscopic instruments used in materials science, mineralogy, and biological sciences for observing microstructures. SEMs are typically equipped with energy dispersive spectroscopy (EDS) to analyze the micro-area composition of samples. To ensure the accuracy of SEM and EDS data, the magnification of the SEM needs frequent calibration during use, and the peak position of the EDS also needs calibration when peak shifts occur. Several SEM and EDS testing standards and methods specify calibration requirements for these instruments.

[0003] Currently, silicon-based grating samples are generally used as reference samples for the magnification of scanning electron microscopes (SEMs). However, the fabrication process for these samples is complex and costly. Simple energy dispersive spectroscopy (EDS) peak calibration reference samples are typically fabricated by attaching copper foil to an aluminum stage or aluminum foil to a copper stage. However, the foil is prone to deformation and bending, making it unsuitable for repeated use. During use, the sample position needs to be adjusted according to the Kα peak heights of aluminum and copper, which is cumbersome. When both SEM magnification and EDS peak positions need to be calibrated simultaneously, two sample loading operations are usually required. Even if both types of samples can be placed on the stage simultaneously, the inconsistent heights of the two samples necessitate repeated adjustments to the working distance of the SEM (i.e., the distance between the sample surface and the lower surface of the SEM pole piece during imaging) and optical path alignment, making the process cumbersome. Therefore, there is a need to develop a multifunctional, easy-to-fabricate, convenient-to-use, and low-cost SEM and EDS calibration sample. Summary of the Invention

[0004] The purpose of this invention is to address the problems of existing scanning electron microscope (SEM) magnification and energy dispersive spectroscopy (EDS) peak position calibration reference samples, which are characterized by limited functionality, complex fabrication processes, high costs, and cumbersome operation. This invention provides a multifunctional SEM and EDS calibration sample, which is easy to fabricate, convenient to operate, and low in cost, along with its preparation method.

[0005] The first objective of this invention is to provide a reference sample for calibrating scanning electron microscopes (SEMs) and energy dispersive spectrometers (EDS). This reference sample can be used to calibrate the magnification of the SEM and the peak positions of the EDS, while also allowing for the measurement of the linear distortion rate of the SEM image, the energy resolution at both the high and low energy ends of the EDS, and the inspection of the peak height ratio at both the high and low energy ends of the EDS.

[0006] A reference sample for calibration of scanning electron microscopes and energy dispersive spectroscopy, the reference sample comprising: a copper-aluminum connector,

[0007] The sample comprises an inlay and a surface carbon film, wherein the copper-aluminum connector is inlaid on the inlay, and the surface carbon film is deposited on the surface of the reference sample; the copper-aluminum connector is provided with scanning electron microscope (SEM) calibration marks (SEM magnification calibration marks) and energy dispersive spectroscopy (EDS) peak position calibration marks, wherein the SEM calibration marks include low-magnification, medium-magnification, and high-magnification calibration marks, and the marks are composed of orthogonal cross grids and are set on the copper side of the copper-aluminum connector; the EDS peak position calibration marks include two marking lines parallel to the copper-aluminum interface and are respectively set on both sides of the copper-aluminum interface; the thickness of the surface carbon film is 1 nm to 10 nm.

[0008] The copper-aluminum connector comprises a pure aluminum block and a pure copper block, wherein the aluminum block contains 99% to 100% aluminum by mass, and the pure copper block contains 99% to 100% copper by mass. The cross-section of the copper-aluminum connector has an aluminum area fraction of 20% to 80% and a copper area fraction of 20% to 80%.

[0009] The copper-aluminum connector is formed by welding the pure copper block and the pure aluminum block. A metal diffusion layer or an intermetallic compound layer may exist between the pure copper block and the pure aluminum block.

[0010] The side length of each square in the cross grid of the low-magnification calibration mark is 40μm to 100μm; the side length of each square in the cross grid of the medium-magnification calibration mark is 4μm to 10μm; and the side length of each square in the cross grid of the high-magnification calibration mark is 400nm to 1μm.

[0011] As an optimization, the scanning electron microscope calibration marks are positioned within a 2mm range of the copper-aluminum interface. The widths of the low-magnification, medium-magnification, and high-magnification calibration marks are 20nm to 1μm.

[0012] As an optimization, the intermediate magnification calibration mark is set within one grid of the low magnification calibration mark, and the high magnification calibration mark is set within one grid of the intermediate magnification calibration mark.

[0013] As an optimization, the energy spectrum peak position calibration markers are positioned within 2 mm of the copper-aluminum interface. The spacing between the two energy spectrum peak position calibration marker lines is 100 μm to 1 mm, and the width of the marker lines is 200 nm to 5 μm, preferably 1 μm to 5 μm.

[0014] As an optimization, the reference sample used for scanning electron microscopy and energy dispersive spectroscopy calibration is a cylindrical embedded sample with a height of 8-12 mm and a diameter of 20-40 mm, with a copper-aluminum connector embedded on one surface of the cylindrical sample.

[0015] This reference sample, used for the calibration of scanning electron microscopes and energy dispersive spectrometers, can be used for the calibration of the magnification of scanning electron microscopes, the determination of the linear distortion rate of images, the calibration of the peak positions of energy dispersive spectrometers, the determination of the energy resolution at the high and low energy ends of energy dispersive spectrometers, and the checking of the peak height ratio at the high and low energy ends of energy dispersive spectrometers.

[0016] The copper side of the sample can be used to check the peak height ratio parameter at the high and low energy ends of the energy dispersive spectrometer, by testing the K of copper. α and L α The peak height ratio can be used to determine whether there is contamination at the low-energy end of the energy dispersive spectrometer. This can be achieved by testing copper K... α The half-width at half-maximum (WHM) can be used to check the energy resolution at the high-energy end of the spectrometer.

[0017] The carbon film on the sample surface can reduce charge accumulation during sample use and slow down the oxidation process. It can also be used to test the carbon element (K). α The half-width at half-maximum (WHM) of the peak is used to detect the energy resolution at the low-energy end of the spectrometer.

[0018] A second objective of this invention is to provide a method for preparing a reference sample for calibration of scanning electron microscopes and energy dispersive spectroscopy (EDS). This method includes steps such as copper-aluminum bonding, cutting, mounting, grinding, polishing, processing marking lines, carbon coating, and sample packaging and preservation.

[0019] A method for preparing a reference sample for scanning electron microscopy and energy dispersive spectroscopy calibration includes the following steps:

[0020] (1) Copper-aluminum connection: connect pure copper blocks and pure aluminum blocks by welding; or select pre-connected components with pure copper and pure aluminum interfaces;

[0021] (2) Cutting: Cut the copper and aluminum blocks obtained in step (1) into cubes with length, width and height all less than 10mm. The cross section of the copper-aluminum connector includes the weld area.

[0022] (3) Mounting: The sample obtained in step (2) is placed into the mounting machine and filled with carbon-containing conductive mounting powder to make a cylindrical mounting sample;

[0023] (4) Grinding: Grind the inlaid sample obtained in step (3) using a grinding and polishing machine;

[0024] (5) Polishing: The sample obtained in step (4) is polished using a polishing machine with a diamond polishing liquid of 1μm to 2.5μm for 5min to 30min.

[0025] (6) Processing the marking line: Place the sample obtained in step (5) in a focused ion beam-electron beam system equipped with an energy dispersive spectrometer, making the copper-aluminum interface perpendicular to the horizontal direction of the screen. Collect energy spectra of the sample within the field of view at 50x to 500x magnification. Move the horizontal position of the copper-aluminum interface to make the K of copper... α peaks and K of aluminum α The relative height difference of the peaks is within 5%. Two energy spectrum peak position calibration marking lines are processed on the left and right boundaries of the energy spectrum acquisition area using a focused ion beam. Low-magnification calibration markings, medium-magnification calibration markings, and high-magnification calibration markings are processed on the copper side of the sample.

[0026] (7) Carbon film deposition: Place the sample obtained in step (6) into a coating instrument and deposit a carbon film of 1 nm to 10 nm on the sample surface.

[0027] In step (1), the welding method includes, but is not limited to, fusion welding, pressure welding, friction welding, laser welding, etc. The weld area should be as small as possible, and components with pure copper and pure aluminum interfaces can also be directly selected; the mass percentage of copper in the pure copper block is 99% to 100%, and the mass percentage of aluminum in the pure aluminum block is 99% to 100%.

[0028] In step (2), the area fraction of aluminum in the cross-sectional area of ​​the copper-aluminum connector is 20% to 80%, and the area fraction of copper is 20% to 80%; avoid areas with obvious welding defects when cutting.

[0029] In step (3), the height of the cylindrical inlay sample is 8-12 mm and the diameter is 20-40 mm; the pressure applied to the inlay material during inlay is 0.5 MPa-3 MPa, the temperature of the inlay material is 150℃-180℃, and the heat preservation time is 2 min-5 min.

[0030] In step (4), the embedded sample obtained in step (3) is placed on the grinding plate of the polishing machine, and the speed of the polishing machine is controlled to be 200 rpm to 400 rpm, and the grit of the polishing sandpaper is 120 to 2000.

[0031] In step (5), the sample obtained in step (4) is placed on the polishing disc of the polishing machine and polished with a diamond polishing slurry of 1μm to 2.5μm for 2min to 30min.

[0032] In step (6), before using the focused ion beam-electron beam system, the magnification factor (including 100x, 1000x and 10000x) used in ion processing is calibrated using traceable standard length materials.

[0033] In step (6), the distance between the two energy spectrum peak calibration marking lines is 100μm to 1mm, and the width of the marking lines is 200nm to 5μm, preferably 1μm to 5μm.

[0034] In step (6), the low-magnification calibration mark includes 5×5 or 10×10 square grids with a side length of 40μm to 100μm, the medium-magnification calibration mark includes 5×5 or 10×10 square grids with a side length of 4μm to 10μm, and the high-magnification calibration mark includes 5×5 or 10×10 square grids with a side length of 400nm to 1μm.

[0035] In step (6), the width of the low-magnification calibration mark, the medium-magnification calibration mark and the high-magnification calibration mark is 20nm to 1μm.

[0036] In step (7), the thickness of the carbon film is 1 nm to 5 nm.

[0037] Sample packaging and preservation: Place the sample obtained in step (7) into a sample box, seal it in plastic and vacuum it for preservation.

[0038] The present invention has the following advantages:

[0039] (1) This calibration reference sample is multifunctional. It can simultaneously calibrate the magnification of the scanning electron microscope and the peak position of the energy dispersive spectrometer, and can also check the peak height ratio at the high and low energy ends of the energy dispersive spectrometer and the energy resolution at the high and low energy ends. The reference sample is convenient to use.

[0040] (2) The preparation process of this calibration reference sample is convenient and low in cost. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of a reference sample used for calibration of scanning electron microscopes and energy dispersive spectrometers;

[0042] Figure 2 Image for low-magnification calibration marking of a scanning electron microscope;

[0043] Figure 3 Image of the magnification calibration mark in a scanning electron microscope;

[0044] Figure 4 Image for high-magnification calibration marking of scanning electron microscope;

[0045] Figure 5 Image of the peak position calibration markers for the energy dispersive spectrometer. Detailed Implementation

[0046] The technical solution of the present invention is not limited to the specific implementation schemes described below, but also includes any combination of the specific implementation schemes.

[0047] like Figure 1 As shown, a reference sample for scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) calibration is provided. The reference sample includes a copper-aluminum connector, SEM magnification calibration markers, EDS peak position calibration markers, an inlay, and a surface carbon film. It can be used for SEM magnification calibration, determination of image linearity distortion, EDS peak position calibration, determination of EDS high and low energy resolution, and checking the peak height ratio at the high and low energy ends of the EDS. The copper-aluminum connector comprises a pure aluminum block and a pure copper block, with the aluminum block containing 99%–100% aluminum by mass and the copper block containing 99%–100% copper by mass. The SEM magnification calibration markers are located on the copper side of the copper-aluminum connector and include low-magnification, medium-magnification, and high-magnification calibration markers. The markers consist of an orthogonal cross grid. The EDS peak position calibration markers include two lines parallel to the copper-aluminum interface. The thickness of the carbon film on the sample surface is 1 nm–10 nm. In the copper-aluminum connector, the pure copper block and the pure aluminum block are connected by welding.

[0048] The scanning electron microscope (SEM) magnification calibration markings on the copper side of the sample include low-magnification, medium-magnification, and high-magnification markings, all composed of orthogonal cross-shaped grids. These markings are located within 2 mm of the copper-aluminum interface. The medium-magnification calibration marking is within one grid within the low-magnification calibration area, and the high-magnification calibration marking is within one grid within the medium-magnification calibration area.

[0049] like Figure 2 As shown, the side length of each small square in the crosshair grid of the low magnification calibration area is 40μm to 100μm, which can be used for calibration of scanning electron microscopes at magnifications of 10 to 500x, and can also be used to measure the linear distortion rate of the scanning electron microscope image; for example Figure 3 As shown, the side length of each small square in the crosshair grid of the medium magnification calibration area is 4μm to 10μm, which can be used for calibration of scanning electron microscopes at magnifications of 500 to 5000x; Figure 4 As shown, the side length of each small square in the cross grid of the high magnification calibration area is 400nm to 1μm, which can be used for calibration at magnifications of 5000 to 100000 times.

[0050] like Figure 5 As shown, the energy dispersive spectroscopy (EDS) peak position calibration markings consist of two lines parallel to the copper-aluminum interface, which can be used to calibrate the peak positions of the EDS. The EDS peak position calibration markings are located within 2 mm of the copper-aluminum interface.

[0051] The method for preparing the reference sample used for scanning electron microscopy and energy dispersive spectroscopy calibration includes the following steps:

[0052] (1) Copper-aluminum connection: pure copper blocks and pure aluminum blocks are connected by welding. The welding method includes, but is not limited to, fusion welding, pressure welding, friction welding, laser welding, etc. The weld area should be as small as possible. Components with pure copper and pure aluminum interfaces can also be directly selected. The mass percentage of copper in the pure copper block is 99% to 100%, and the mass percentage of aluminum in the pure aluminum block is 99% to 100%.

[0053] (2) Cutting: Cut the pure copper and pure aluminum blocks obtained in step (1) into cubes with a cross-section length, width and height of less than 10 mm. The cross-section of the cube includes the weld area and avoids the area with obvious welding defects. The area fraction of copper in the cross-section of the cube is 20% to 80% and the area fraction of aluminum is 20% to 80%.

[0054] (3) Mounting: The sample obtained in step (2) is placed into the mounting machine and loaded with carbon-containing conductive mounting powder to prepare a cylindrical mounting sample with a height of 8-12 mm and a diameter of 20 mm-40 mm. The pressure applied to the mounting material during mounting is 0.5 MPa-3 MPa, the mounting material temperature is 150℃-180℃, and the holding time is 2 min-5 min.

[0055] (4) Grinding: Place the embedded sample obtained in step (3) on the grinding plate of the grinding and polishing machine, control the speed of the grinding and polishing machine to be 200 rpm to 400 rpm, and the grit of the sandpaper on the grinding and polishing surface to be 120 to 2000.

[0056] (5) Polishing: Place the sample obtained in step (4) on the polishing plate of the polishing machine, and polish it with diamond polishing liquid of 1μm to 2.5μm for 2min to 30min.

[0057] (6) Processing the marking lines: Place the sample obtained in step (5) into a focused ion beam-electron beam system equipped with an energy spectrometer, so that the copper-aluminum interface is roughly perpendicular to the horizontal direction of the screen. Collect the energy spectrum of the sample within the field of view at 50x to 500x magnification. Move the horizontal position of the copper-aluminum interface so that the relative height difference between the Kα peak of copper and the Kα peak of aluminum is within 5%. Use a focused ion beam to process two energy spectrum peak position calibration marking lines with a spacing of 100μm to 1mm on the left and right boundaries of the energy spectrum acquisition area, respectively. The width of the marking lines is 1μm to 5μm. Process low magnification calibration markings, medium magnification calibration markings and high magnification calibration markings on the copper side of the sample, respectively.

[0058] Before use, focused ion beam-electron beam systems should be calibrated using traceable standard-length materials for each magnification level used in ion processing. The spacing between the two energy spectrum peak marker lines should be 100 μm to 1 mm, and the width of the marker lines should be 200 nm to 5 μm. Low-magnification calibration markers consist of a 5×5 or 10×10 square grid with sides of 40 μm to 100 μm. Medium-magnification calibration markers consist of a 5×5 or 10×10 square grid with sides of 4 μm to 10 μm. High-magnification calibration markers consist of a 5×5 or 10×10 square grid with sides of 400 nm to 1 μm. The width of the low-magnification, medium-magnification, and high-magnification calibration markers should be 20 nm to 1 μm.

[0059] (7) Carbon film deposition: Place the sample obtained in step (6) into a coating instrument and deposit a carbon film of 1 nm to 5 nm on the sample surface.

[0060] (8) Sample packaging and preservation: Place the sample obtained in step (7) into a sample box, seal it in plastic and vacuum it for preservation.

[0061] Example 1:

[0062] Pure copper (copper mass percentage greater than 99%) and pure aluminum (aluminum mass percentage greater than 99%) were joined by pressure welding. Samples were cut into 10mm long and wide sections and 5mm high using wire cutting, with each copper and aluminum side being 5mm wide. The samples were then placed in an inlay machine and loaded with carbon-containing conductive inlay powder to create cylindrical inlay samples with a height of 10mm and a diameter of 40mm. During the inlay process, the pressure of the inlay machine was 0.5MPa, the heating temperature range was 150℃~180℃, and the holding time was 5min. The inlaid samples were then placed on a polishing machine at a speed of 200rpm, using sandpaper grit ranging from 120 to 2000 grit, with the final sandpaper grit set to 2000 grit. The mechanically polished sample was placed on the polishing disc of a polishing machine and polished with 1μm diamond polishing slurry for 10 minutes. Before use, the magnification of the focused ion beam-electron beam system equipped with an energy dispersive spectrometer was calibrated at 100x, 1000x, and 10000x using traceable standard length materials. The polished sample was placed in the calibrated focused ion beam-electron beam system, with the copper-aluminum interface perpendicular to the horizontal direction of the screen. Energy spectra were collected within the sample's field of view at 100x magnification. The horizontal position of the copper-aluminum interface was moved to adjust the K0 of copper. α peaks and K of aluminum αThe relative height difference of the peaks was within 5%. Two marker lines with a spacing of 800 μm and a width of 2 μm were fabricated at the left and right boundaries of the energy dispersive spectroscopy (EDS) acquisition region using a focused ion beam. On the copper side of the sample, calibration markers were fabricated as follows: low-magnification calibration markers consisting of a 10×10 square grid with a side length of 100 μm and a line width of 1 μm; medium-magnification calibration markers consisting of a 10×10 square grid with a side length of 10 μm and a line width of 100 nm; and high-magnification calibration markers consisting of a 10×10 square grid with a side length of 1 μm and a line width of 20 nm. The sample was placed in a coating apparatus, and a carbon film of approximately 1 nm thickness was deposited on the sample surface. The sample was then placed in a sample box, sealed in plastic, and vacuum-sealed for storage.

[0063] Example 2:

[0064] Components with pure copper and pure aluminum interfaces—copper-aluminum nose components connected by friction welding—were selected as raw materials. The copper-aluminum noses were cut to a width of 5mm on both the copper and aluminum sides. The sample was placed in an mounting machine, and carbon-containing conductive mounting powder was added to prepare a cylindrical mounting sample with a height of 10mm and a diameter of 20mm. During the mounting process, the pressure of the mounting machine was 0.5MPa, the heating temperature was 150℃, the holding time was 5min, and the cooling time was 2min. The mounted sample was then placed on the grinding disc of a polishing machine, with the polishing machine speed controlled at 200rpm. The sandpaper grit for the polishing surface was 120 to 2000 grit, with the final sandpaper grit being 2000 grit. The mechanically polished sample was placed on the polishing disc of a polishing machine and polished with 2.5 μm diamond polishing slurry for 5 minutes. Before use, the magnification of the focused ion beam-electron beam system equipped with an energy dispersive spectrometer was calibrated at 200x, 2000x, and 20000x using traceable standard length materials. The polished sample was placed in the aforementioned focused ion beam-electron beam system, with the copper-aluminum interface perpendicular to the horizontal direction of the screen. Energy spectra were collected within the sample's field of view at 200x magnification. The horizontal position of the copper-aluminum interface was moved to adjust the K0 of copper. α peaks and K of aluminum α The relative height difference of the peaks was within 5%. Two marker lines with a spacing of 500 μm and a width of 1 μm were fabricated at the left and right boundaries of the energy spectrum acquisition range using a focused ion beam. On the copper side of the sample, calibration markers were fabricated as follows: low-magnification calibration markers consisting of a 5×5 square grid with a side length of 50 μm and a marker line width of 500 nm; medium-magnification calibration markers consisting of a 5×5 square grid with a side length of 5 μm and a marker line width of 100 nm; and high-magnification calibration markers consisting of a 5×5 square grid with a side length of 50 nm and a marker line width of 20 nm. The sample was placed in a coating apparatus, and a carbon film of approximately 2 nm thickness was deposited on the sample surface. The sample was then placed in a sample box, sealed in plastic, and vacuum-sealed for preservation.

[0065] Example 3:

[0066] Copper-clad aluminum wire with a diameter of 2 mm and a copper volume fraction of 15% was selected as the raw material. The copper-clad aluminum wire was cut into 1 mm segments using a slow-speed saw. The cross-section of the copper-clad aluminum wire was placed face down in an inlay machine, and carbon-containing conductive inlay powder was added to prepare a cylindrical inlay sample with a height of 8 mm and a diameter of 20 mm. During the inlay process, the pressure of the inlay machine was 0.5 MPa, the heating temperature range was 150℃~180℃, and the holding time was 5 min. The inlaid sample was then placed on the polishing disc of a polishing machine, with the polishing machine speed controlled at 200 rpm. The sandpaper grit for the polishing surface ranged from 120 to 2000 grit, with the final sandpaper grit set to 2000 grit. The mechanically polished sample was placed on the polishing disc of a polishing machine and polished for 5 minutes using 2.5 μm diamond polishing slurry, followed by 5 minutes using 1.0 μm diamond polishing slurry. Before use, the magnification of the focused ion beam-electron beam system equipped with an energy dispersive spectrometer was calibrated at 200x, 2000x, and 20000x using traceable standard length materials. The polished sample was placed in the aforementioned focused ion beam-electron beam system, with the copper-aluminum interface approximately perpendicular to the horizontal direction of the screen. Energy spectra were collected within the sample's field of view at 2000x magnification. The horizontal position of the copper-aluminum interface was moved to adjust the K0 of copper. α peaks and K of aluminum α The relative height difference of the peaks was within 5%. Two marker lines with a spacing of 50 μm and a width of 1 μm were fabricated at the left and right boundaries of the energy spectrum acquisition range using a focused ion beam. On the copper side of the sample, calibration markers were fabricated as follows: low-magnification calibration markers consisting of a 5×5 square grid with a side length of 40 μm and a marker line width of 500 nm; medium-magnification calibration markers consisting of a 5×5 square grid with a side length of 4 μm and a marker line width of 100 nm; and high-magnification calibration markers consisting of a 5×5 square grid with a side length of 400 nm and a marker line width of 20 nm. The sample was placed in a coating apparatus, and a carbon film of approximately 2 nm thickness was deposited on the sample surface. The sample was then placed in a sample box, sealed in plastic, and vacuum-sealed for preservation.

[0067] The reference sample for scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) calibration in this invention includes pure copper, pure aluminum, calibration markings, embedded materials, and surface carbon films. The preparation steps involve welding pure copper and pure aluminum blocks together, embedding them in conductive powder, and then grinding and polishing them. In a focused ion beam-electron beam system, the position of the copper-aluminum interface is adjusted so that the characteristic X-rays K0 of copper-aluminum acquired by the EDS are... αWith a peak relative height difference within 10%, two vertical lines are fabricated at the edge of the field of view using a focused ion beam. Three types of squares with side lengths ranging from 400 nm to 100 μm are fabricated on the pure copper side near the aforementioned region. The sample is then coated with a thin carbon film and vacuum-sealed for preservation. The sample involved in this invention can be used for checking and calibrating multiple parameters of scanning electron microscopy, such as magnification, image linearity distortion, energy spectrum peak position, energy resolution, and the ratio of high to low energy peak heights. This preparation method is simple to operate, low in cost, suitable for laboratory preparation, and the reference sample is convenient and quick to use during the calibration process.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. All simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A method for preparing a reference sample for calibration of scanning electron microscopy and energy dispersive spectroscopy, characterized in that, Includes the following steps: (1) Copper-aluminum connection: connect the pure copper block and the pure aluminum block by welding; or select pre-connected components with pure copper and pure aluminum interfaces; (2) Cutting: Cut the copper and aluminum blocks obtained in step (1) into cubes with length, width and height all less than 10 mm. The cross section of the copper-aluminum connector includes the weld area. (3) Mounting: The sample obtained in step (2) is placed into the mounting machine, and carbon-containing conductive mounting powder is added to make a cylindrical mounting sample; (4) Grinding: Grind the inlaid sample obtained in step (3) using a grinding and polishing machine; (5) Polishing: The sample obtained in step (4) is polished using a polishing machine with a diamond polishing liquid of 1 μm to 2.5 μm for 5 min to 30 min. (6) Processing the marking line: Place the sample obtained in step (5) in a focused ion beam-electron beam system equipped with an energy dispersive spectrometer, making the copper-aluminum interface perpendicular to the horizontal direction of the screen, and collect the energy spectrum of the sample within the field of view at 50x to 500x magnification. Move the horizontal position of the copper-aluminum interface so that the K of copper is... α peaks and K of aluminum α The relative height difference of the peaks is within 5%. Two energy spectrum peak position calibration marking lines are processed at the left and right boundaries of the energy spectrum acquisition range using a focused ion beam. Low-magnification calibration markings, medium-magnification calibration markings, and high-magnification calibration markings are processed on the copper side of the sample. (7) Carbon film deposition: Place the sample obtained in step (6) into a coating instrument and deposit a carbon film of 1 nm to 10 nm on the sample surface.

2. The method for preparing a reference sample for scanning electron microscopy and energy dispersive spectroscopy calibration according to claim 1, characterized in that, The pressure applied to the mounting material during mounting is 0.5MPa to 3MPa, the temperature of the mounting material is 150℃ to 180℃, and the holding time is 2min to 5min. The mounted sample is placed on the grinding disc of a polishing machine, and the speed of the polishing machine is controlled at 200 rpm to 400 rpm. The grit of the polishing sandpaper is 120 to 2000 grit. Before use, the focused ion beam-electron beam system is calibrated using traceable standard length materials for each magnification used in ion processing.

3. A reference sample for calibration of scanning electron microscopy and energy dispersive spectroscopy, characterized in that, It is prepared by the method described in claim 1 or 2.

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