Method for preparing porous carbon membrane transmission electron microscopy grid using soft template having porous array structure

Abstract

A method for preparing a porous carbon membrane transmission electron microscopy grid using a soft template having a porous array structure. The method comprises the following steps: transferring a soft template having a porous array structure onto a grid surface of a transmission electron microscopy grid, depositing a carbon membrane on the surface of the transmission electron microscopy grid, and removing the soft template to obtain a carbon membrane transmission electron microscopy grid having a porous array structure. The preparation method is simple and practical, highly reproducible, and broadly applicable. The obtained carbon membrane transmission electron microscopy grid exhibits an excellent grid structure quality, has the potential for batch preparation, and can also be directly used for the preparation of a graphene electron microscopy grid meeting transmission electron microscopy sample preparation requirements; and the latter can be applied to single-particle cryo-electron microscopy three-dimensional structural analysis and high-resolution imaging of nanoparticles and single atoms.

Description

A method for preparing a porous carbon film transmission electron microscope grid by using a soft template with a porous array structure TECHNICAL FIELD

[0001] The present application relates to the field of materials, in particular to a method for preparing a porous carbon film transmission electron microscope grid by using a soft template with a porous array structure. BACKGROUND

[0002] When the morphology of biological sample materials is characterized by a transmission electron microscope, the quality of the transmission electron microscope grid loaded with the sample is crucial to the characterization result of the sample. At present, the preparation technology of high-quality transmission electron microscope grids can meet the needs of scientific research to a certain extent. However, the production cycle of transmission electron microscope grids is relatively long, the gap in scientific research demand is relatively large, and the production cost is high. On the other hand, the current transmission electron microscope grids are discrete structures, which are not conducive to the batch operation of subsequent grid modification and hinder the smooth development of scientific research.

[0003] In order to alleviate the gap in the demand for transmission electron microscope grids and reduce the production cost, a batch preparation method of high-quality transmission electron microscope grids is indispensable. The process route of depositing a metal film or an amorphous alloy film on a hard silicon template with a microarray hole by using thermal evaporation or magnetron sputtering technology (patent numbers CN201810326897.5 and CN202110333466.3) can effectively realize the preparation of a metal film or an alloy film transmission electron microscope grid with a porous array structure, and support the subsequent transfer of a graphene supporting film to meet higher scientific research needs. However, common metal films (such as porous gold films) are polycrystalline films, which are not conducive to the focusing and astigmatism requirements of high-resolution transmission electron microscopy; the preparation of amorphous alloy film grids puts high requirements on the instrument, and it is also difficult to realize large-area preparation and transfer of the amorphous alloy film with a porous array structure.

[0004] At present, the carbon film grid with a porous array structure is still the most commonly used type of grid in the field of transmission electron microscopy. On the one hand, since the porous carbon film is amorphous, it can meet the requirements of astigmatism in high-resolution transmission electron microscopy; on the other hand, the relative atomic mass of carbon element is smaller than that of metal element, and the contrast under the electron microscope is lower, which relatively small interference to the imaging of the sample. However, for the preparation of high-quality porous carbon film transmission electron microscope grids, although there is a process for preparing a porous carbon film transmission electron microscope grid by using a fluorine film with a porous array structure (patent number 202010189490.X), the process is complex, the production efficiency is low, and it is difficult to realize batch production. At the same time, the grid produced by the process has organic residues, which will affect the grid modification and is difficult to meet the current scientific research needs. Therefore, it is necessary to develop a new method for preparing a porous carbon film transmission electron microscope grid to meet the needs of batch production and modification of transmission electron microscope grids. SUMMARY

[0005] The preparation method of the present application is to transfer the soft template with a porous array structure to the surface of a transmission electron microscope grid, then deposit a carbon film on the surface of the transmission electron microscope grid, remove the soft template, and prepare a carbon film transmission electron microscope grid with a porous array structure.

[0006] The method of the present application is simple, easy to operate, highly repeatable, and has universality; the grid structure of the obtained carbon film transmission electron microscope grid has excellent quality and has the potential for batch preparation, and can be directly used for the preparation of graphene electron microscope grids that meet the sample preparation requirements of transmission electron microscopes, which can be used for single-particle three-dimensional structure analysis of cryo-EM and high-resolution imaging of nanoparticles and single atoms. Technical problem

[0007] The purpose of the present application is to provide a method for preparing a porous carbon film transmission electron microscope grid using a soft template with a porous array structure, which effectively realizes the preparation of a high-quality carbon film transmission electron microscope grid with a uniform and complete porous array structure. Technical solution

[0008] The present application first provides a method for preparing a carbon film transmission electron microscope grid with a porous array structure, comprising the following steps:

[0009] (1) transferring a soft template with a porous array structure to the surface of a transmission electron microscope grid to obtain a transmission electron microscope grid with a soft template with a porous array structure;

[0010] (2) depositing a carbon film on the surface of the transmission electron microscope grid with a soft template with a porous array structure to obtain an electron microscope grid grid with a porous array structure carbon film;

[0011] (3) removing the soft template in the electron microscope grid grid with a porous array structure carbon film to obtain the carbon film transmission electron microscope grid with a porous array structure.

[0012] In the above preparation method, the soft template with a porous array structure is a metal soft template with a porous array structure or a photoresist soft template with a porous array structure;

[0013] The material of the transmission electron microscope grid is gold, copper, nickel or silicon nitride;

[0014] In step (2), the thickness of the carbon film is 20-50 nm; specifically, it can be 30 nm or 35 nm.

[0015] In the above preparation method, the specification of the transmission electron microscope grid is 200-3000 mesh, specifically 300 mesh.

[0016] In the preparation method, the material of the metal soft template with the porous array structure is a non-inert metal element that is easy to be etched; and the metal element can be copper or nickel.

[0017] The photoresist soft template with the porous array structure is a positive photoresist or a negative photoresist.

[0018] The thickness of the soft template with the porous array structure is 30-1000 nm; and the thickness can be 50 nm or 800 nm.

[0019] In the preparation method, the pattern of the porous array structure is a circular hole; and the diameter of the circular hole can be 0.1-5 μm, and specifically, the diameter can be 0.8-1.2 μm; and the period of the circular hole pattern can be 0.2-10 μm, and specifically, the period can be 2.5 μm.

[0020] In the preparation method, in step (1), the method for transferring the soft template with the porous array structure to the surface of a transmission electron microscope grid includes the following steps:

[0021] S1, transferring the soft template with the porous array structure to the water surface of a container containing water;

[0022] S2, placing the transmission electron microscope grids one by one on the bottom of the container after the transmission electron microscope grids are treated by plasma hydrophilization;

[0023] S3, controlling the liquid surface to descend at a constant speed, adjusting the position of the soft template with the porous array structure, and until the soft template with the porous array structure is in flat contact with the transmission electron microscope grid; and a transmission electron microscope grid with the soft template with the porous array structure is obtained.

[0024] In the method for transferring the soft template with the porous array structure to the surface of a transmission electron microscope grid, after the soft template with the porous array structure is in flat contact with the transmission electron microscope grid, a drying step is further included; and specifically, the drying is normal-temperature, light-avoiding, and ventilated drying.

[0025] In the preparation method, optionally, a filter paper is placed on the bottom of the container containing water, and the transmission electron microscope grids are placed one by one on the surface of the filter paper; and optionally, a pair of tweezers is used to adjust the position of the soft template with the porous array structure, so that the soft template is always located above the transmission electron microscope grid.

[0026] In the preparation method, in step (2), a carbon film is prepared by using a thermal evaporation method or a magnetron sputtering method.

[0027] Specifically, the conditions of the thermal evaporation method are as follows:

[0028] The evaporation carbon source is a carbon rod, a carbon wire, or a carbon rope.

[0029] The evaporation vacuum degree is 10 -2 ~10 -4 Pa; specifically, 10 -3 Pa;

[0030] The evaporation current is 30-75 A; specifically, 55 A or 60 A.

[0031] In the preparation method, the number of times of adjusting the evaporation carbon process can adjust the thickness of the carbon film with a porous array structure.

[0032] In step (3), the method for removing the soft template in the electron microscope grid with a porous array structure carbon film includes: soaking the electron microscope grid with a porous array structure carbon film in an etching reagent to remove the soft template; specifically, the soaking time is 1-3 min, and more specifically, 2 min.

[0033] In the preparation method, a suitable etching reagent is selected according to the type of the soft template; specifically, the etching reagent for removing the metal soft template can be one or more of hydrochloric acid solution, ammonium persulfate solution or ferric chloride solution according to the type of the metal; the etching reagent for removing the photoresist soft template can be one or more of N-methyl-2-pyrrolidone, nitrogen ethyl pyrrolidone, acetone and isopropyl alcohol.

[0034] In the preparation method, in step (1), the preparation method of the soft template with a porous array structure includes the following steps: preparing a metal soft template with a porous array structure on the surface of a hard template or preparing a photoresist soft template with a porous array structure on the surface of a hard substrate; peeling the metal soft template with a porous array structure from the surface of the hard template or peeling the photoresist soft template with a porous array structure from the surface of the hard substrate.

[0035] Specifically, when peeling, the inclination angle of the soft template with a porous array structure is 20-60 degrees, and specifically, 30-45 degrees; the separation speed can be 0.05-0.5 cm / s, and specifically, 0.1 cm / s.

[0036] There is a sacrificial layer between the hard template and the metal soft template, and the sacrificial layer can be at least one of sodium metaphosphate, sodium chloride and potassium chloride; the thickness of the sacrificial layer can be 10-500 nm, and specifically, 20-100 nm.

[0037] There is a sacrificial layer between the hard substrate and the photoresist soft template, and the sacrificial layer can be one or more of non-inert metal substrates such as copper and nickel; the thickness of the sacrificial layer can be 100-1000 nm, and specifically, 200 nm.

[0038] The reagent for stripping the soft template with the porous array structure can be one or more of deionized water, hydrochloric acid, ammonium persulfate solution or ferric chloride solution, according to the material of the soft template.

[0039] The size of the hard template or hard substrate can be 1-12 inches, and specifically can be 4 inches.

[0040] The material of the hard template or hard substrate is quartz, sapphire, silicon wafer or silicon nitride.

[0041] In the preparation method, after the soft template in the carbon film with a porous array structure in the electron microscope grid is removed in step (3), there are still washing and drying steps; specifically, the reagent for washing can be one or more of isopropyl alcohol, acetone and water.

[0042] The washing is to immerse the sample in the reagent; specifically, the immersion time can be 1-3 min, and specifically can be 2 min.

[0043] The drying environment is normal temperature and normal pressure, and the drying time can be 2-10 min.

[0044] The application further provides a carbon film transmission electron microscope grid with a porous array structure prepared by the above preparation method.

[0045] The application of the above carbon film transmission electron microscope grid with a porous array structure in transmission electron microscope grid preparation or low-temperature cryo-EM also belongs to the protection scope of the application. Advantages

[0046] The preparation process of the application is simple, can realize the preparation of a wafer-level large-area soft template with a porous array structure, and the prepared soft template has excellent quality, good repeatability, high parallelism and large-scale batch preparation potential; at the same time, compared with a commercial grid, the carbon film transmission electron microscope grid with a porous array structure prepared by the application is more flat and has smaller undulations; and batch preparation of transmission electron microscope grids can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0047] Fig. 1 is a flowchart of preparing a carbon film transmission electron microscope grid with a porous array structure by using a soft template with a porous array structure according to the application;

[0048] Fig. 2 is an optical characterization of the transmission electron microscope grid with a porous array structure prepared in step (3) in Example 1; wherein, A in Fig. 2 is a low-resolution optical microscope image; and B is a high-resolution optical microscope image.

[0049] Figure 3 is an optical characterization of the carbon film transmission electron microscope grid with a porous array structure prepared in Example 1; wherein Figure 3A is a low resolution optical microscope image; and Figure 3B is a high resolution optical microscope image;

[0050] Figure 4 is a scanning electron microscope image of the carbon film transmission electron microscope grid with a porous array structure prepared in Example 1; wherein Figure 4A is a low resolution scanning electron microscope image; and Figure 4B is a high resolution scanning electron microscope image;

[0051] Figure 5 is a transmission electron microscope image of the carbon film transmission electron microscope grid with a porous array structure prepared in Example 1; wherein Figure 5A is a low resolution transmission electron microscope image; and Figure 5B is a high resolution transmission electron microscope image;

[0052] Figure 6 is an optical characterization of the soft template with a porous array structure prepared in step (3) of Example 2; wherein Figure 6A is a low resolution optical microscope image; and Figure 6B is a high resolution optical microscope image;

[0053] Figure 7 is an optical characterization of the carbon film transmission electron microscope grid with a porous array structure prepared in Example 2; wherein Figure 7A is a low resolution optical microscope image; and Figure 7B is a high resolution optical microscope image;

[0054] Figure 8 is a scanning electron microscope image of the carbon film transmission electron microscope grid with a porous array structure prepared in Example 2; wherein Figure 8A is a low resolution scanning electron microscope image; and Figure 8B is a high resolution scanning electron microscope image;

[0055] Figure 9 is a transmission electron microscope image of the carbon film transmission electron microscope grid with a porous array structure prepared in Example 2; wherein the left image is a low resolution transmission electron microscope image; and the right image is a high resolution transmission electron microscope image. Embodiments of the present application

[0056] The present application will be further described in details with reference to the specific embodiments, and the embodiments are only for illustrating the present application, but not for limiting the scope of the present application. The experimental methods in the following embodiments are all conventional methods, unless otherwise specified. The materials, reagents, instruments, etc. used in the following embodiments are all commercially available, unless otherwise specified. The quantitative experiments in the following embodiments are all set up with three repeated experiments, and the results are averaged.

[0057] In the following examples, the photoresist soft template with a porous array structure is made by a UV exposure machine, with an exposure wavelength of 365 nm and an exposure time of 4-10 seconds; the positive photoresist is AR-P 5350; the developing solution is AR 300-26, with a developing formula of (AR 300-26): water = 1:7 (volume ratio); and the fixing solution is pure water.

[0058] In the following examples, the carbon film with a porous array structure is made by a high-vacuum ion sputtering coating instrument.

[0059] The prepared porous array structure carbon film transmission electron microscope grid is characterized, including a metal soft template with a porous array structure obtained by a thermal evaporation or a magnetron sputtering method, a photoresist soft template with a porous array structure obtained by a photolithography method, and a carbon film with a porous array structure obtained by an evaporation method. The measurement method is as follows:

[0060] A Nikon upright metallographic microscope, model LV100ND, or a scanning electron microscope (Hitachi S-4800) is used. The optical microscope or the scanning electron microscope can clearly characterize the morphology of the photoresist soft template and the structure and morphology of the transmission electron microscope grid array.

[0061] The flowchart of the preparation process of the carbon film transmission electron microscope grid with a porous array structure of the present application is shown in FIG. 1. The method for preparing the porous carbon film transmission electron microscope grid using the soft template with a porous array structure can be divided into three steps: preparing and transferring the porous soft template, sputtering / evaporating amorphous carbon, and removing the porous soft template.

[0062] Example 1: Preparation of a carbon film transmission electron microscope grid with a porous array structure using a copper soft template with a porous array structure.

[0063] The specific implementation process is as follows:

[0064] (1) Preparation of a copper soft template with a porous array structure: a thermal evaporation vacuum coating instrument is used to evaporate a 30 nm thick sodium metaphosphate sacrificial layer on a 2.5x2.5 cm square silicon template with a circular hole array structure (circular hole diameter 1.2 μm, circular hole pattern period 2.5 μm, square arrangement), with a vacuum degree of 5x10 -3 Pa and a coating rate of 0.12 Å / s. A 50 nm thick copper layer is continuously evaporated, with a vacuum degree of 1x10 -3 Pa and a coating rate of 0.1 Å / s.

[0065] (2) Separation of the copper soft template with porous array structure from the silicon template: using tweezers to hold one corner of the sample obtained in (1), slowly immerse the composite structure in a container containing deionized water at an angle of 45° to realize the separation of the copper soft template from the silicon template. Control the separation speed to be 0.1 cm / s until the template is completely immersed and the copper soft template floats completely on the water surface.

[0066] (3) Preparation of a transmission electron microscope grid with a soft template with a porous array structure: transfer the sample obtained in (2) to the water surface of a container containing deionized water, and place the transmission electron microscope grid mesh (manufacturer: GILDER GRIDS, item number: AG300G) treated by plasma hydrophilization (in this embodiment, a plasma cleaning instrument (Germany Diener, Pico) is used; air flow is 5 sccm, power is 150 W, and treatment time is 10 min) one by one at the bottom of the container containing deionized water. Control the uniform descent of the liquid surface (in this embodiment, a container with a drain at the bottom is used, and the water flow is controlled by a rubber tube + iron clamp to control the uniform descent of the liquid surface), and adjust the position of the copper soft template with a porous array structure until the copper soft template is in flat contact with the upper surface of the transmission electron microscope grid mesh. After drying (normal temperature, light shielding, ventilation drying), the transmission electron microscope grid with a soft template with a porous array structure is obtained; its optical characterization is shown in FIG. 2. As can be seen from FIG. 2, after the copper soft template is transferred to the surface of the transmission electron microscope grid mesh, the integrity and flatness are excellent.

[0067] (4) Preparation of a carbon film with a porous array structure: deposit a layer of carbon film on the sample obtained in (3) using a carbon evaporator. The evaporation source is a carbon rod, the evaporation vacuum degree is 10 -3 Pa, the evaporation current is 60 A, and a carbon film with a porous array structure with a thickness of 35 nm is obtained.

[0068] (5) Removal of the copper soft template with a porous array structure: immerse the sample obtained in (4) in a 1 mol / L aqueous ammonium persulfate solution for 2 min, then immerse the sample in isopropanol for 2 min. After drying, a carbon film transmission electron microscope grid with a porous array structure is obtained.

[0069] The optical characterization of the carbon film transmission electron microscope grid with a porous array structure prepared in this embodiment is shown in FIG. 3. As can be seen from FIG. 3, the carbon film with a porous array structure has high flatness and no obvious undulations. The scanning electron microscope image is shown in FIG. 4. As can be seen from FIG. 4, the carbon film with a porous array structure has high integrity, high coverage, and a clean surface without plugging. The transmission electron microscope image is shown in FIG. 5. As can be seen from FIG. 5, the porous carbon film surface is clean, the pore size is about 1.2 μm, the copper soft template is completely removed, and there is no obvious metal residue.

[0070] Example 2: Preparation of carbon film TEM grid with porous array structure by using photoresist soft template with porous array structure.

[0071] The specific implementation process is as follows:

[0072] (1) Preparation of metal thin film substrate: a copper thin film was sputtered on the surface of a quartz wafer using a magnetron sputtering instrument, the sputtering temperature was room temperature, the sputtering power was 150 W, the sputtering time was 60 min, the sputtering atmosphere was Ar, and the sputtering pressure was 0.13 Pa, and a copper thin film with a thickness of 500 nm was obtained.

[0073] (2) Preparation of photoresist soft template with porous array structure: a photoresist soft template with porous array structure (thickness 800 nm) was prepared on the surface of the copper thin film by photolithography.

[0074] The specific method is as follows:

[0075] (a) spin-coat positive photoresist AR-P 5350 on the surface of the copper thin film at a spin-coating rate of 6000 r / min;

[0076] (b) bake the photoresist at 100°C for 1 min;

[0077] (c) place the photoresist plate on the surface of the photoresist and expose it to ultraviolet light under the ultraviolet light machine, the exposure time is 8 s;

[0078] (d) bake the sample (photoresist / copper thin film / quartz wafer) after exposure at 100°C for 3 min;

[0079] (e) immerse the baked sample in the developing solution for 40 s, then immerse it in the fixing solution for 1 min, and dry it with nitrogen.

[0080] (3) Preparation of TEM grid with soft template of porous array structure: The sample obtained in (2) was immersed in 1 mol / L aqueous ammonium persulfate solution. After the metal film substrate was completely removed, the soft template of photoresist and the hard substrate composite structure was taken out of the etching solution and slowly immersed in a container containing deionized water at an angle of 30° until the soft template of photoresist floated completely on the water surface. The TEM grid grid (manufacturer: GILDER GRIDS, item number: AG300G) treated by plasma hydrophilization (this embodiment specifically uses a plasma cleaning instrument (Germany Diener, Pico); air flow 5 sccm, power 150 W, treatment time 10 min) was placed one by one at the bottom of the container containing deionized water, and the liquid surface was controlled to descend at a constant speed, and the position of the soft template of photoresist was adjusted until the soft template of photoresist was in flat contact with the upper surface of the TEM grid grid. After the sample was dried (dried at room temperature, away from light and ventilation), the TEM grid with soft template of porous array structure was obtained; its optical characterization is shown in Figure 6; as can be seen from Figure 6, after the soft template of photoresist is transferred to the surface of the TEM grid grid, it still maintains a high degree of integrity, and is well combined with the surface of the grid grid with high flatness.

[0081] (4) Preparation of carbon film with porous array structure: A layer of carbon film was deposited on the surface of the sample obtained in (3) using a carbon evaporator. The carbon source for evaporation was a carbon rod, the evaporation vacuum degree was 10 -3 Pa, the evaporation current was 55 A, and a carbon film with a thickness of 30 nm and a porous array structure was obtained.

[0082] (5) Removal of the soft template of photoresist with a porous array structure: The sample obtained in (4) was immersed in acetone for 2 min and then taken out, and then the sample was immersed in isopropyl alcohol for 2 min and then taken out. After the sample was dried, a carbon film TEM grid with a porous array structure was obtained.

[0083] The optical characterization of the carbon film TEM grid with a porous array structure prepared in this example is shown in Figure 7, and as can be seen from Figure 7, the carbon film with a porous array structure has high flatness and no obvious undulations. The scanning electron microscope image is shown in Figure 8, and as can be seen from Figure 8, the carbon film with a porous array structure is completely covered and the surface is clean without any blockage. The transmission electron microscope image is shown in Figure 9, and as can be seen from Figure 9, the surface of the porous carbon film is clean, the pore size is about 1.2 μm, the soft template of photoresist is completely removed, and there is no obvious organic residue. Industrial applicability

[0084] The application utilizes a periodic porous array structure soft template to prepare a carbon film with a porous array structure, and the prepared carbon film has good integrity, high flatness, and high yield and production efficiency, which can meet the requirements of large-scale batch preparation; the prepared porous array structure carbon film transmission electron microscope grid reaches the commercial standard, and batch preparation of the transmission electron microscope grid can be realized.

Claims

1. A method for preparing a carbon film transmission electron microscope grid having a porous array structure, characterized by: The method comprises the following steps: (1) transferring the soft template with a porous array structure to the surface of a transmission electron microscope grid, to obtain a transmission electron microscope grid with a soft template with a porous array structure; (2) depositing a carbon film on the surface of the transmission electron microscope grid with the soft template with a porous array structure, to obtain an electron microscope grid grid with a carbon film with a porous array structure; (3) removing the soft template in the electron microscope grid grid with the carbon film with a porous array structure, to obtain a carbon film transmission electron microscope grid with a porous array structure.

2. The production method according to claim 1, characterized by: The soft template with a porous array structure is a metal soft template with a porous array structure or a photoresist soft template with a porous array structure; The material of the transmission electron microscope grid is gold, copper, nickel or silicon nitride; In step (2), the thickness of the carbon film is 20-50 nm.

3. The method of claim 2, wherein: The metal soft template with a porous array structure is made of a non-inert metal element that is easy to be etched; The photoresist soft template with a porous array structure is a positive photoresist or a negative photoresist; The thickness of the soft template with a porous array structure is 30-1000 nm.

4. The method of claim 1, wherein: In step (1), the method for transferring the soft template with a porous array structure to the surface of a transmission electron microscope grid comprises the following steps: S1, transferring the soft template with a porous array structure to the water surface of a container containing water; S2, placing the transmission electron microscope grid one by one on the bottom of the container after plasma hydrophilization treatment; S3, controlling the liquid surface to descend uniformly, adjusting the position of the soft template with a porous array structure, until the soft template with a porous array structure is in flat contact with the transmission electron microscope grid; to obtain the transmission electron microscope grid with the soft template with a porous array structure.

5. The method of claim 1, wherein: In step (2), the carbon film is prepared by thermal evaporation or magnetron sputtering; In step (3), the method for removing the soft template in the electron microscope grid grid with the carbon film with a porous array structure comprises immersing the electron microscope grid grid with the carbon film with a porous array structure in an etching reagent to remove the soft template.

6. The method of claim 5, wherein: The conditions for thermal evaporation are as follows: The evaporation carbon source is a carbon rod, a carbon wire or a carbon rope; The vacuum degree of the evaporation is 10 -2 ~10 -4 Pa; The evaporation current is 30-75 A.

7. The production method according to claim 2 or 5, characterized by: In step (3), the etching reagent for removing the metal soft template is one or more of hydrochloric acid, ammonium persulfate solution or ferric chloride solution, according to the type of metal; The etching reagent for removing the photoresist soft template is one or more of N-methyl-2-pyrrolidone, nitrogen ethyl pyrrolidone, acetone or isopropyl alcohol.

8. The method of claim 1, wherein: In step (1), the method for preparing the soft template with a porous array structure comprises the following steps: preparing a metal soft template with a porous array structure on the surface of a hard template or preparing a photoresist soft template with a porous array structure on the surface of a hard substrate; peeling the metal soft template with a porous array structure from the surface of the hard template or peeling the photoresist soft template with a porous array structure from the surface of the hard substrate; There is a sacrificial layer between the hard template and the metal soft template, and the sacrificial layer is at least one of sodium metaphosphate, sodium chloride and potassium chloride; There is a sacrificial layer between the hard substrate and the photoresist soft template, and the sacrificial layer is a non-inert metal; The material of the hard template or hard substrate is quartz, sapphire, silicon wafer or silicon nitride.

9. The carbon film TEM grid with porous array structure prepared by the method of any one of claims 1-8.

10. The use of the carbon film TEM grid with porous array structure of claim 9 in the preparation of TEM grid or cryo-EM.

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