Method for preparing cross-sectional samples of thin film materials based on laser-induced thermal fracture brittle substrates using scanning electron microscopy

Abstract

A scanning electron microscope (SEM) cross-sectional sample preparation method for thin film materials based on a laser-heat-broken brittle substrate, belonging to the field of thin film materials, includes: fabricating the thin film to be tested on a brittle substrate; dispersing light-absorbing nanoparticles in an organic solvent to prepare an ink, followed by ultrasonic dispersion, with the dispersion temperature controlled by a water bath; filtering the dispersed ink to obtain ITO nanoparticle ink; setting a driving waveform to obtain ITO droplets; heating the brittle substrate on which the thin film to be tested has been prepared; setting printing parameters and printing patterns to start inkjet printing to obtain light-absorbing material lines; heating the brittle substrate on which the thin film to be tested and the light-absorbing material lines have been prepared; adjusting the laser spot diameter and laser parameters, setting the laser scanning path, and starting the laser to perform sintering treatment to achieve fracture of the brittle substrate; and performing SEM analysis on the fractured substrate. This invention has the advantages of simple operation, smooth fracture surface, high sample preparation efficiency, wide applicability, low cost, and repeatability.

Description

Technical Field

[0001] This invention belongs to the field of thin film materials technology, specifically relating to a method for preparing cross-sectional samples of thin film materials using scanning electron microscopy based on a laser-induced thermal fracture brittle substrate. Background Technology

[0002] Scanning electron microscopy (SEM) plays a crucial role in materials science, particularly in the study of thin film materials. By enabling high-resolution imaging of the morphology of thin film cross-sections and precise elemental analysis, researchers can gain in-depth understanding of the microstructure and compositional distribution of thin films. This is essential for the development and optimization of new materials, directly impacting their performance in electronic devices, optical components, and energy materials.

[0003] However, preparing cross-sectional samples of thin film materials for SEM analysis is a challenging task. Traditional methods, such as cryofraction, can fracture the ceramic substrate supporting the thin film to expose the cross-section for observation, but they suffer from high costs and low yields. Furthermore, cryofraction can damage the sample, affecting the accuracy of the observation results. Another commonly used method is ion beam cutting, but this method is expensive, complex to operate, and may introduce processing damage, limiting its widespread application.

[0004] Therefore, there is an urgent need for a low-cost, rapid, and effective method for preparing thin film cross-sections to meet the requirements of SEM analysis. Summary of the Invention

[0005] The purpose of this invention is to provide a scanning electron microscope (SEM) cross-sectional sample preparation method for thin film materials based on laser-induced thermal fracture brittle substrates. This method can significantly reduce sample preparation costs, shorten the sample preparation cycle, and improve sample quality. This not only helps to accelerate the optimization process of new materials but also promotes the rapid development of related fields, thereby enhancing scientific research efficiency and innovation capabilities.

[0006] The technical solution adopted by this invention to solve the technical problem is as follows:

[0007] This invention provides a method for preparing cross-sectional samples of thin film materials using scanning electron microscopy based on a laser-induced thermal fracture brittle substrate, comprising the following steps:

[0008] S101: Fabrication of the thin film to be tested on a brittle substrate;

[0009] S102: Disperse the light-absorbing material nanoparticles in an organic solvent to prepare an ink; use an ultrasonic disruptor to ultrasonically disperse the ink and control the dispersion temperature of the ink through a water bath; filter the dispersed ink with a 0.45μm polytetrafluoroethylene filter membrane to obtain ITO nanoparticle ink; set the driving waveform to obtain ITO droplets; heat-treat the brittle substrate on which the film to be tested is prepared; set the printing parameters and printing pattern to start inkjet printing and obtain the light-absorbing material line.

[0010] S103: Heat the brittle substrate with the prepared thin film and light-absorbing material circuit; adjust the laser spot diameter, set the laser scanning path, adjust the laser parameters, turn on the laser to perform sintering treatment, realize the fracture of the brittle substrate, and obtain the thermal stress fracture substrate.

[0011] S104: Scanning electron microscopy analysis of the thermally stressed fractured substrate.

[0012] In a preferred embodiment, the brittle substrate material is an alumina substrate or a single-crystal silicon substrate.

[0013] In a preferred embodiment, the thin film material to be tested is indium oxide and copper.

[0014] In a preferred embodiment, the absorbance of the light-absorbing material is not less than 0.7 at room temperature.

[0015] In a preferred embodiment, the light-absorbing material is indium tin oxide.

[0016] In a preferred embodiment, the parameters of the driving waveform are: positive voltage 65-75V, negative voltage 70-80V, reference voltage 0-3V, positive voltage rise time 5-6ms, positive voltage duration 30-35ms, positive voltage fall time 10-15ms, negative voltage duration 40-42ms, and negative voltage rise time 5-6ms.

[0017] In a preferred embodiment, the printing parameters are: horizontal printing dot spacing of 0.034-0.036 mm, vertical printing dot spacing of 0.04-0.045 mm, and printing speed of 15-17 mm / s.

[0018] In a preferred embodiment, the printed pattern is a rectangle with a width of 2 mm, which extends laterally through the entire brittle substrate, and the distance between the upper edge of the rectangle and the film to be tested is no more than 5 mm.

[0019] In a preferred embodiment, the brittle substrate on which the thin film to be tested and the light-absorbing material circuitry are prepared is heated to 50-55°C.

[0020] In a preferred embodiment, the laser spot diameter is 0.2-0.3 mm, the laser scanning path is a zigzag pattern, and the laser parameters are: laser power 50-60 W, scanning speed 50-70 mm / s, and scanning line spacing 0.001-0.0015 mm; the scanning area is a 2×10 mm rectangle, and the scanning start position is controlled on the light-absorbing material line in the middle of the brittle substrate.

[0021] The beneficial effects of this invention are:

[0022] 1. High efficiency and precision. High-energy lasers are used to precisely scan the light-absorbing material circuitry, and the brittle substrate is induced to fracture through local temperature gradients. Compared with traditional freezing brittle fracture methods or mechanical cutting methods, this method is simple to operate, produces a smooth crack surface, and has higher sample preparation efficiency. The average speed for large-scale sample preparation can reach 1 minute per sample.

[0023] 2. Wide applicability. This method is applicable to a variety of brittle substrate materials (such as ceramics, single-crystal silicon, etc.) and can optimize parameters for different substrates and thin film materials. It is highly flexible and can meet the sample preparation needs of various thin film materials.

[0024] 3. Low cost and repeatability. The efficient utilization of laser energy is achieved through the light-absorbing material circuit, eliminating the need for expensive freezing equipment or complex mechanical devices, significantly reducing sample preparation costs. Furthermore, both the light-absorbing material circuit and laser parameters are easily standardized and replicated, ensuring the controllability and consistency of the sample preparation method. Attached Figure Description

[0025] Figure 1 This invention provides a schematic diagram of the sample preparation process for a scanning electron microscope (SEM) cross-section sample preparation method for thin film materials based on a laser-induced thermal fracture brittle substrate.

[0026] Figure 2 This invention provides a method for preparing thin film samples of In2O3 on an alumina substrate using a scanning electron microscope cross-section method for preparing thin film materials based on a laser-induced thermal fracture brittle substrate.

[0027] Figure 3 This invention provides a method for preparing thin film samples on a single-crystal silicon substrate using a scanning electron microscope (SEM) cross-section of a thin film material based on a laser-induced thermal fracture brittle substrate. Detailed Implementation

[0028] This invention provides a new method for preparing cross-sectional samples of thin film materials for scanning electron microscopy based on laser-induced thermal fracture brittle substrates. This method is low-cost, fast, and yields high-quality samples.

[0029] The core innovation of this invention is: by printing light-absorbing material lines on a brittle substrate, and then using a high-energy laser to scan the light-absorbing material lines to form an extremely high temperature gradient, the brittle substrate is fractured, and finally a cross-sectional sample is made for scanning electron microscopy (SEM) analysis.

[0030] like Figure 1 As shown, the present invention provides a method for preparing a cross-sectional sample of a thin film material based on a laser-fractured brittle substrate using scanning electron microscopy, which mainly includes four steps: preparation of the thin film to be tested, preparation of the light-absorbing material circuit, laser fracture of the brittle substrate, and scanning electron microscopy imaging.

[0031] (1) Preparation of the thin film to be tested: The thin film sample to be photographed and measured is prepared on a brittle substrate;

[0032] (2) Fabrication of light-absorbing material circuit: Light-absorbing material circuit is printed on a brittle substrate on which the thin film to be tested has been prepared by inkjet printing technology or other additive manufacturing technology;

[0033] (3) Laser fracture of brittle substrate: High-energy laser is used to sinter light-absorbing material circuits back and forth. The laser energy is efficiently converted into heat through the light-absorbing material circuits, forming an extremely high temperature gradient in a local area. This temperature gradient causes rapid thermal stress concentration in the local area of ​​the brittle substrate, thereby inducing brittle fracture, forming a flat fracture surface, and exposing the cross section of the film to be tested, ultimately forming a thermal stress fracture substrate.

[0034] (4) Scanning electron microscopy (SEM) analysis: The thermal stress fracture substrate was photographed with a scanning electron microscope to perform cross-sectional morphology and elemental characterization.

[0035] The present invention provides a method for preparing cross-sectional samples of thin film materials using scanning electron microscopy based on laser-induced thermal fracture brittle substrates. The specific implementation process is as follows:

[0036] S101: Fabricating thin film samples that require photographing and measurement on a brittle substrate;

[0037] First, the materials of the brittle substrate and the film to be tested are determined. Common brittle substrate materials include ceramics (such as alumina, zirconium oxide, etc.), single-crystal silicon, glass, and other non-metallic inorganic materials. It is particularly important to note that, except for special toughened composite materials, other non-metallic inorganic material substrates are suitable for this invention. The following quantitative criteria can be used to select brittle substrate materials suitable for this invention: the quantitative criterion is the material's fracture toughness K. IC Below 8 MPa·m -1 At the same time, the substrate thickness needs to be ensured to be 0.5mm-1.5mm.

[0038] In a preferred embodiment, the present invention selects an alumina substrate and a single-crystal silicon substrate as brittle substrates for manufacturing thin film samples.

[0039] Common thin film materials include metal thin films, semiconductor thin films, and insulating ceramic thin films. It is particularly important to note that any chemically stable thin film with a thickness not exceeding 200 μm is suitable for this invention.

[0040] In a preferred embodiment, indium oxide (In2O3) and copper (Cu) are selected as the materials for the thin film to be tested in this invention.

[0041] Secondly, existing thin-film manufacturing techniques are used to fabricate the thin-film samples to be measured on the selected brittle substrate material. Specifically, an In2O3 thin film is fabricated on an alumina substrate, and a Cu thin film is fabricated on a monocrystalline silicon substrate. The specific steps for fabricating the In2O3 thin film on the alumina substrate are as follows: the alumina substrate is rinsed with isopropanol, ethylene glycol, and ultrapure water for at least 5 seconds, and after rinsing with ultrapure water, the alumina substrate is dried using a hot air gun; then, existing thin-film manufacturing techniques, such as physical vapor deposition, direct-write deposition, and molecular beam surface growth, are used on the cleaned alumina substrate. In this invention, inkjet printing technology (direct-write deposition) is used to prepare the In2O3 thin film to be characterized. The specific steps for fabricating the Cu thin film on the monocrystalline silicon substrate are as follows: the monocrystalline silicon substrate is rinsed with isopropanol, ethylene glycol, and ultrapure water for at least 5 seconds, and after rinsing with ultrapure water, the monocrystalline silicon substrate is dried using a hot air gun; then, inkjet printing technology is used to prepare the Cu thin film to be characterized on the cleaned monocrystalline silicon substrate.

[0042] S102: Inkjet printing of light-absorbing material circuits;

[0043] S1021: First, select a light-absorbing material. The absorbance of the light-absorbing material needs to be set according to the wavelength of the laser used in this invention.

[0044] Based on experimental experience, the laser wavelength used in this invention is 1064nm. Therefore, the absorbance of the light-absorbing material only needs to be no less than 0.7 at room temperature.

[0045] In a preferred embodiment, indium tin oxide (ITO) is selected as the light-absorbing material in this invention, which has an absorbance of 0.79 for 1064 nm wavelength radiation at room temperature.

[0046] S1022: Then, the nanoparticles of the light-absorbing material are dispersed in an organic solvent to prepare an ink with a mass fraction of 8-10%. As a preferred embodiment, the organic solvent in this invention is a mixed solution of ethylene glycol and isopropanol, with a mass ratio of ethylene glycol to isopropanol of 0.8-1.

[0047] S1023: Use an ultrasonic disruptor to ultrasonically disperse the ink at a power of 120-200W for 2-4 hours, and control the ink dispersion temperature to 10-15℃ using a water bath.

[0048] S1024: The dispersed ink is filtered through a 0.45μm polytetrafluoroethylene (PTFE) filter membrane to obtain ITO nanoparticle ink that can be used for inkjet printing.

[0049] S1025: Set the driving waveform of the droplet ejection device to obtain highly stable ITO droplets under an appropriate driving waveform.

[0050] In a preferred embodiment, the driving waveform parameters set in this invention are as follows:

[0051] Positive voltage 65-75V, negative voltage 70-80V, reference voltage 0-3V, positive voltage rise time 5-6ms, positive voltage duration 30-35ms, positive voltage fall time 10-15ms, negative voltage duration 40-42ms, negative voltage rise time 5-6ms.

[0052] S1026: Using a temperature-controlled heating stage, after setting the heating temperature, heat the brittle substrate on which the thin film to be tested has been prepared;

[0053] As a preferred embodiment, the alumina substrate is heated to 140-160°C; the monocrystalline silicon substrate is heated to 110-120°C.

[0054] S1027: Set printing parameters and print pattern through host computer software to start inkjet printing and obtain light-absorbing material lines.

[0055] As a preferred embodiment, the printing parameters are: horizontal printing dot spacing of 0.034-0.036mm, vertical printing dot spacing of 0.04-0.045mm, and printing speed of 15-17mm / s.

[0056] In a preferred embodiment, the printed pattern of the light-absorbing material is a rectangle with a width of 1.5mm-2mm. This rectangular pattern extends laterally across the entire brittle substrate, and the distance between the upper edge of the rectangular pattern and the film under test is no greater than 5mm. It is crucial to avoid contaminating the film under test during the inkjet printing process.

[0057] S103: Laser-fractured brittle substrate;

[0058] S1031: Place the brittle substrate with the prepared thin film and light-absorbing material circuitry on a temperature-controlled heating stage, set the heating temperature to 50-55℃, and start heating.

[0059] S1032: Adjust the laser spot diameter to 0.2-0.3mm.

[0060] As a preferred embodiment, the laser used in this invention is a continuous-wave Nd-YAG laser with a wavelength of 1064 nm.

[0061] S1033: Set the laser scanning path.

[0062] In a preferred embodiment, the laser scanning path in this invention is a zigzag pattern.

[0063] S1034: Adjust the laser parameters of the laser.

[0064] In a preferred embodiment, the laser parameters in this invention are set as follows: laser power 50-60W, scanning speed 50-70mm / s, and scanning line spacing 0.001-0.0015mm.

[0065] In a preferred embodiment, the scanning area is set as a 2×10mm rectangle, and the scanning start position is controlled on the light-absorbing material lines in the middle of the brittle substrate, such as... Figure 1 As shown.

[0066] S1035: The laser of the laser is turned on to perform sintering treatment, realize the fracture of the brittle substrate, and obtain a thermal stress fracture substrate.

[0067] S104: Scanning electron microscopy (SEM) analysis;

[0068] The thermally stressed fractured substrate is picked up and subsequently cleaned to remove any impurities or debris that may remain on the surface. Then, it is mounted on a scanning electron microscope (SEM) platform for SEM analysis to obtain the morphology and elemental distribution information of the cross-section of the thin film under test.

[0069] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0070] Example 1: Method for preparing cross-sectional samples of thin film materials for scanning electron microscopy based on laser-induced thermal fracture brittle substrates

[0071] (1) Select an alumina substrate as a brittle substrate with a thickness of 1.0 mm; select In2O3 material as the material of the film to be tested; rinse the alumina substrate with isopropanol, ethylene glycol and ultrapure water for at least 5 s respectively; after rinsing with ultrapure water, blow the alumina substrate dry with a hot air gun; prepare the In2O3 film to be characterized on the cleaned alumina substrate using inkjet printing technology.

[0072] (2) ITO was selected as the light-absorbing material, with an absorbance of 0.79 for 1064nm radiation at room temperature. ITO nanoparticles were dispersed in a mixed solution of ethylene glycol and isopropanol (mass ratio of ethylene glycol to isopropanol was 0.9) to prepare an ink with a mass fraction of 9%. The ink was ultrasonically dispersed for 3 hours at 150W using an ultrasonic disruptor, and the dispersion temperature was controlled at 15℃ using a water bath. The dispersed ink was filtered through a 0.45μm polytetrafluoroethylene filter membrane to obtain ITO nanoparticle ink suitable for inkjet printing. The driving waveform of the droplet ejection device was set as follows: positive pressure 70V, negative pressure 75V, reference voltage 2V, positive pressure rise time 5ms, positive pressure... The duration was 30ms, the positive pressure drop time was 15ms, the negative pressure duration was 41ms, and the negative pressure rise time was 5ms; highly stable ITO droplets were obtained under this driving waveform; the alumina substrate with the prepared In2O3 film was heated to 150℃ using a temperature-controlled heating stage; the printing parameters (horizontal printing dot spacing of 0.035mm, vertical printing dot spacing of 0.04mm, printing rate of 16mm / s) and the printing pattern (the printing pattern is a rectangular pattern with a width of 2mm and the distance between the upper edge of the rectangular pattern and the In2O3 film is no more than 5mm, and the rectangular pattern runs horizontally through the entire alumina substrate) were set through the upper computer software to start inkjet printing and obtain the ITO material line.

[0073] (3) The alumina substrate with the prepared In2O3 thin film and ITO material line was placed on a temperature-controlled heating stage and heated to 52°C; the spot diameter of the continuous wave Nd-YAG laser (wavelength 1064nm) was adjusted to 0.25mm; the laser scanning path was set to zigzag mode; the laser parameters were adjusted as follows: laser power 55W, scanning speed 60mm / s, scanning line spacing 0.001mm, scanning area set to a 2×10mm rectangle, and the scanning start position was controlled on the ITO material line in the middle of the alumina substrate; the laser was turned on to perform sintering treatment to achieve the fracture of the alumina substrate and obtain the thermal stress fractured alumina substrate.

[0074] (4) Pick up the thermal stress fractured alumina substrate, perform subsequent cleaning treatment to remove any impurities or debris that may remain on the surface, and then install it on the scanning electron microscope observation platform for scanning electron microscope analysis to obtain the morphology and elemental distribution information of the In2O3 thin film cross section.

[0075] Among them, the In2O3 thin film sample fabricated on an alumina substrate using a scanning electron microscope cross-sectional sample preparation method for thin film materials based on a laser-induced thermal fracture brittle substrate provided by the present invention is as follows: Figure 2As shown, the photographed film cross-section can distinguish In2O3 film with a thickness of 2.8μm-3μm from an alumina substrate. The In2O3 film and the alumina substrate cross-section are at the same depth of field, and the images are clear, which proves the excellent imaging characteristics of the film cross-section produced by this method.

[0076] Example 2: Method for preparing cross-sectional samples of thin film materials for scanning electron microscopy based on laser-induced thermal fracture brittle substrates

[0077] (1) Select a single crystal silicon substrate as a brittle substrate with a thickness of 1.0 mm; select Cu material as the material of the thin film to be tested; rinse the single crystal silicon substrate with isopropanol, ethylene glycol and ultrapure water for at least 5 s respectively; after rinsing with ultrapure water, blow the single crystal silicon substrate to dry with a hot air gun; prepare the Cu thin film to be characterized on the cleaned single crystal silicon substrate using inkjet printing technology.

[0078] (2) ITO was selected as the light-absorbing material, which has an absorbance of 0.79 for 1064nm radiation at room temperature. The ITO nanoparticles were dispersed in a mixed solution of ethylene glycol and isopropanol (mass ratio of ethylene glycol to isopropanol was 0.9) to prepare an ink with a mass fraction of 9%. The ink was ultrasonically dispersed for 3 hours at 150W using an ultrasonic disruptor, and the dispersion temperature was controlled at 15℃ using a water bath. The dispersed ink was filtered through a 0.45μm polytetrafluoroethylene filter membrane to obtain ITO nanoparticle ink suitable for inkjet printing. The driving waveform of the droplet ejection device was set as follows: positive pressure 70V, negative pressure 75V, reference voltage 2V, and positive pressure rise time 5ms. The positive pressure duration was 30ms, the positive pressure drop time was 15ms, the negative pressure duration was 41ms, and the negative pressure rise time was 5ms. Under this driving waveform, highly stable ITO droplets were obtained. Using a temperature-controlled heating stage, the single-crystal silicon substrate with the prepared Cu thin film was heated to 115℃. The printing parameters (horizontal printing dot spacing of 0.035mm, vertical printing dot spacing of 0.04mm, printing rate of 16mm / s) and the printing pattern (the printing pattern is a rectangular pattern with a width of 2mm and the distance between the upper edge of the rectangular pattern and the Cu thin film is no more than 5mm, and the rectangular pattern runs horizontally through the entire single-crystal silicon substrate) were set through the upper computer software to start inkjet printing and obtain ITO material lines.

[0079] (3) Place the prepared Cu thin film and ITO material circuit on a temperature-controlled heating stage and heat it to 52°C; adjust the spot diameter of the continuous wave Nd-YAG laser (wavelength 1064nm) to 0.25mm; set the laser scanning path to zigzag mode; adjust the laser parameters as follows: laser power 55W, scanning speed 60mm / s, scanning line spacing 0.001mm, scanning area set to a 2×10mm rectangle, and control the scanning start position on the ITO material circuit in the middle of the single crystal silicon substrate; turn on the laser to perform sintering treatment to achieve the fracture of the single crystal silicon substrate and obtain a thermal stress fractured single crystal silicon substrate.

[0080] (4) Pick up the thermal stress fractured single crystal silicon substrate, perform subsequent cleaning treatment to remove any impurities or debris that may remain on the surface, and then install it on the scanning electron microscope observation platform for scanning electron microscope analysis to obtain the morphology and elemental distribution information of the Cu thin film cross section.

[0081] Among them, the Cu thin film sample fabricated on a single-crystal silicon substrate using a scanning electron microscope cross-sectional sample preparation method for thin film materials based on a laser-induced thermal fracture brittle substrate provided by this invention is as follows: Figure 3 As shown, the photographed thin film cross-section can distinguish Cu thin films with a thickness of 7.5μm-7.8μm from single-crystal silicon substrates. The cross-sections of the Cu thin film and the single-crystal silicon substrate are at the same depth of field, and the images are clear, which proves the excellent imaging characteristics of the thin film cross-section produced by this method.

[0082] 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. However, 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 preparing a cross-section of a thin film material for scanning electron microscopy based on laser thermal cleaving of a brittle substrate, characterized in that, The method comprises the following steps: S101: manufacturing a to-be-tested thin film on a brittle substrate; the to-be-tested thin film material is indium oxide or copper; and the brittle substrate material is an aluminum oxide substrate or a single crystal silicon substrate; S102: dispersing nano-particles of light-absorbing material into an organic solvent to configure ink; performing ultrasonic dispersion on the ink by using an ultrasonic disrupter, and controlling the dispersion temperature of the ink by a water bath; filtering the dispersed ink by using a 0.45 μm polytetrafluoroethylene filter membrane to obtain ITO nano-particle ink; setting a driving waveform to obtain an ITO droplet; and performing heating treatment on the brittle substrate with the prepared to-be-tested thin film; setting printing parameters and a printing pattern to start inkjet printing to obtain a light-absorbing material line; S103: performing heating treatment on the brittle substrate with the prepared to-be-tested thin film and the light-absorbing material line; adjusting a laser spot diameter, setting a laser scanning path, adjusting laser parameters, and starting the laser to perform sintering treatment to realize brittle substrate fracture and obtain a thermal stress fractured substrate; S104: performing scanning electron microscope analysis on the thermal stress fractured substrate.

2. The method for preparing a cross-section of a thin film material for a scanning electron microscope according to claim 1, wherein The absorbance of the light-absorbing material is not less than 0.7 at room temperature.

3. The method of claim 1, wherein the brittle substrate is a glass substrate. The parameters of the driving waveform are as follows: positive voltage 65-75 V, negative voltage 70-80 V, reference voltage 0-3 V, positive voltage rising time 5-6 ms, positive voltage duration time 30-35 ms, positive voltage falling time 10-15 ms, negative voltage duration time 40-42 ms, and negative voltage rising time 5-6 ms.

4. The method for cross-section sample preparation of thin film materials scanning electron microscopy based on laser thermal cleavage of brittle substrate according to claim 1, characterized in that, The printing parameters are as follows: horizontal printing point spacing 0.034-0.036 mm, vertical printing point spacing 0.04-0.045 mm, and printing speed 15-17 mm / s.

5. The method for cross-section sample preparation of thin film materials scanning electron microscopy based on laser thermal cleavage of brittle substrate according to claim 1, wherein, The printing pattern is a rectangle with a width of 2 mm, the rectangle pattern horizontally penetrates through the entire brittle substrate, and the distance between the upper edge of the rectangle pattern and the to-be-tested thin film is not greater than 5 mm.

6. The method for cross-section sample preparation of thin film materials scanning electron microscopy based on laser thermal cleavage of brittle substrate according to claim 1, wherein, The brittle substrate with the prepared to-be-tested thin film and the light-absorbing material line is heated to 50-55 ℃.

7. The method of claim 1, wherein the method further comprises: The laser spot diameter is 0.2-0.3 mm, the laser scanning path is a zigzag mode, and the laser parameters are as follows: laser power 50-60 W, scanning speed 50-70 mm / s, scanning line spacing 0.001-0.0015 mm; the scanning area is a rectangle with a size of 2*10 mm, and the scanning starting position is controlled on the light-absorbing material line in the middle of the brittle substrate.

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