A device and method for preventing pollution and blockage of a scanning electron microscope cold stage system

Abstract

The application discloses a device and method for preventing pollution and blockage of a cold stage system of a scanning electron microscope, the device comprising a main low-temperature gas path system and a normal-temperature nitrogen branch, low-temperature nitrogen discharged from the main low-temperature gas path system is divided into two paths, and is respectively connected to a cold hydrazine and a cold stage and is independently controlled through a flow valve. In order to solve the problems that a sample is easily polluted and a gas path is easily blocked during temperature rising in the prior art, a normal-temperature nitrogen branch is additionally arranged on the cold stage gas path through a three-way valve. During a system temperature rising stage, the cold stage low-temperature gas path is closed and the normal-temperature nitrogen branch is opened, dry nitrogen is blown to the cold stage, the cold stage is rapidly heated under positive pressure protection, meanwhile, the cold hydrazine continuously obtains low-temperature nitrogen, and an ultralow temperature is maintained. The above-mentioned measures ensure that a large temperature difference (such as > 150 DEG C) always exists between the cold hydrazine and the cold stage, ensure that pollutants are preferentially captured by the cold hydrazine, effectively protect the surface of the sample to be clean, and fundamentally prevent the gas path from being blocked due to moisture backflow.

Description

Technical Field

[0001] This invention relates to laboratory equipment for electron microscopes (SEM), and in particular to a device and method for preventing contamination and clogging in the cold stage system of a scanning electron microscope, which solves the problems of condensation and sample contamination during the heating process of the cold stage in an electron microscope. Background Technology

[0002] Scanning electron microscopy (SEM) or dual-beam systems (such as the FEI Helios CX5) are essential analytical tools in materials science, life sciences, and semiconductor technology. Systems equipped with cold stages enable cryogenic processing and analysis of samples, which is crucial for studying materials highly sensitive to temperature, electron beams, or ion beams. The importance of cryogenic sample preparation is increasingly evident, especially in the following cutting-edge research areas: 1. In lithium-ion battery research, key components such as the electrolyte, solid electrolyte interphase (SEI), and lithium metal anode are highly susceptible to decomposition, volatilization, and radiation damage under high-energy electron / ion beam irradiation. Furthermore, these components are chemically unstable in vacuum and at room temperature. Cryogenic FIB (Freezing Intake) technology can "freeze" these sensitive materials in their original state at liquid nitrogen temperatures, thus preparing high-quality thin sections for transmission electron microscopy (TEM) observation. This technique can accurately reveal the electrode-electrolyte interface structure, lithium dendrite morphology, and the chemical composition of the SEI film, minimizing artifacts introduced during sample preparation. 2. Sensitive functional materials such as metal-organic frameworks (MOFs) and perovskites. Metal-organic frameworks (MOFs) possess extremely high specific surface areas and tunable pore structures, but their crystal framework stability is often poor. Under high vacuum and electron beam irradiation, MOFs are prone to structural collapse or amorphization, leading to the loss of their unique pore information. Perovskite materials (especially halide perovskites) are extremely sensitive to electron beam irradiation, thermal effects, and vacuum environments, and are highly susceptible to phase transitions, decomposition, and precipitation of heavy metals (such as lead) during characterization. Cryogenic fibrillation (FIB) technology allows researchers to precisely locate, cut, and transport samples at low temperatures, effectively suppressing irradiation damage and thermal effects, thereby obtaining accurate experimental data reflecting the intrinsic structure of the materials. 3. Biological samples, including cells, protein crystals, and tissues. These samples are naturally rich in water; in a vacuum environment, they dehydrate and collapse instantly, completely losing their physiological morphology. Conventional FIB processing would cause devastating damage to their structure. Cryo-electron microscopy (a key pretreatment step in cryo-electron microscopy) perfectly immobilizes the natural conformation of biomolecules by converting water in the sample into amorphous glassy ice at extremely low temperatures. This makes it possible to prepare frozen sections suitable for high-resolution three-dimensional reconstruction using fibrillation-in-the-brush (FIB).

[0003] Therefore, cryogenic FIB technology occupies an important position in modern materials science and plays a crucial role in the study of temperature-sensitive materials, lithium batteries, and other high-precision microscopic analysis fields.

[0004] Existing cold stage systems typically work in conjunction with a cold hydrazine (or cold trap). During cooling, the gas tubing connecting the cold stage and the cold hydrazine is immersed in a liquid nitrogen tank for cooling, with the gas flow rate controlled separately by flow meters. During rewarming, both the cold stage and the cold hydrazine need to be heated to return to room temperature. However, if the temperature difference between the cold stage and the cold hydrazine is small, contaminants may adhere to the sample surface during the heating process, affecting experimental results. The rewarming process involves removing the external gas tubing from the liquid nitrogen tank and maintaining a certain nitrogen flow rate to slowly heat the system to room temperature.

[0005] This heating method has two significant technical drawbacks: 1. Sample contamination risk: During slow heating, if the temperature difference between the cold stage and the cold hydrazine is insufficient, water vapor and contaminants condensed on the surface of the cold hydrazine may evaporate prematurely and re-condense on the relatively cool sample surface, causing the sample to "adhere to dirt" and affecting the accuracy of the observation results; 2. Gas path blockage risk: To address the above problems, operators sometimes attempt to accelerate the heating of the cold stage by shutting off the gas flow meter leading to it. However, this causes gas stagnation in the cold stage's gas path. Due to the low temperature of the pipeline, external humid air will be drawn back into the pipeline, causing internal water vapor to condense into ice, thus blocking the gas path. This not only damages the delicate flow control components but also affects the smooth progress of subsequent experiments.

[0006] Therefore, there is an urgent need in this field for a technical solution that can effectively prevent sample contamination and avoid gas path blockage during the heating process. Summary of the Invention

[0007] To address the problems of condensation and sample contamination during the heating process of a cold stage in existing technologies, this invention provides a device and method for preventing contamination and clogging in a scanning electron microscope cold stage system. This method optimizes the airflow configuration to maintain a large temperature difference in the cold stage during heating, preventing condensation and accelerating heating, thereby improving experimental efficiency and reducing the risk of sample contamination.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A device for preventing contamination and blockage in a scanning electron microscope cold stage system includes a vacuum chamber and a cold stage, a cold hydrazine, an electron gun pole piece and an ion gun disposed in the vacuum chamber. It also includes a main cryogenic gas path system and a normal temperature nitrogen branch with a branch normal temperature nitrogen control valve. The main cryogenic gas circuit system includes a liquid nitrogen Dewar tank and a first inlet pipe. Inert gas is introduced into the inlet end of the first inlet pipe. The middle part of the first inlet pipe can be moved up and down into the liquid nitrogen Dewar tank. The outlet end of the first inlet pipe is divided into two paths. The first path is connected to the gas inlet of the cold hydrazine through a first branch pipe equipped with a cold hydrazine flow valve. The second path is connected to the gas inlet of the cold stage through a second branch pipe equipped with a cold stage flow valve. The inlet of the ambient temperature nitrogen branch is connected to an ambient temperature nitrogen source, and its outlet is connected to the second branch pipeline through a T-connector.

[0009] Furthermore, the intake end of the first intake pipe is connected to a room temperature nitrogen source.

[0010] Furthermore, the nitrogen source at room temperature uses nitrogen cylinders.

[0011] Furthermore, the gas outlets of the cold stage and the cold hydrazine are respectively connected to nitrogen gas outlet pipes, and both nitrogen gas outlet pipes extend to the outside of the vacuum chamber.

[0012] The method for preventing contamination and clogging in a scanning electron microscope cold stage system according to the present invention includes the following steps: S1 Normal Cooling / Low Temperature Holding Stage: The branch ambient temperature nitrogen control valve is closed, and the middle of the first inlet pipe is inserted into the liquid nitrogen in the liquid nitrogen Dewar tank. Ambient temperature nitrogen is introduced into the inlet end of the first inlet pipe. After the ambient temperature nitrogen exchanges heat with the liquid nitrogen in the liquid nitrogen Dewar tank, low temperature nitrogen is formed. The corresponding flow valves on the first branch pipe and the second branch pipe are opened. After the low temperature nitrogen is discharged from the liquid nitrogen Dewar tank, it is simultaneously supplied to the cold hydrazine and the cold stage, so that the entire system is in a low temperature state. S2 system heating phase: S2.1 Maintaining the cold trap at low temperature: The first branch pipeline is always kept unobstructed, and the cold trap continuously receives low-temperature nitrogen gas to maintain its trapping capacity; S2.2 Switching the cold stage gas path: Close the cold stage flow valve on the second branch pipeline to cut off the low-temperature nitrogen flowing to the cold stage; at the same time, open the branch normal temperature nitrogen control valve to allow dry normal temperature nitrogen to enter the second branch pipeline, purge the gas path of the cold stage, and maintain the flow of dry normal temperature nitrogen in the pipeline. S2.3 Start heating function: Turn on the heating mode of the cold table, so that it can be heated up quickly under the protection of nitrogen at room temperature; S2.4 Stop heating: After the cold stage reaches the target temperature, close the branch room temperature nitrogen control valve, adjust the insertion depth of the middle part of the first air inlet pipe so that it is above the liquid nitrogen liquid surface in the liquid nitrogen Dewar tank, stop the supply of low temperature nitrogen to the cold trap, and switch to room temperature nitrogen to allow the cold trap to slowly heat up to room temperature.

[0013] Furthermore, in the step of maintaining the supply of cryogenic gas flow to the cold trap, the middle part of the first air inlet pipe is always immersed in liquid nitrogen in the liquid nitrogen Dewar canister.

[0014] Furthermore, when introducing room temperature nitrogen into the cold trap, the middle part of the first inlet pipe extends above the liquid nitrogen surface inside the liquid nitrogen Dewar container.

[0015] Furthermore, in step S1, the temperature difference between the cold hydrazine and the cold platform is controlled at 30-40℃, the temperature of the cold hydrazine is lower than the temperature of the cold platform, and the temperature of the cold hydrazine is maintained at -192℃±10℃.

[0016] Furthermore, in step S2.4, the cold stage is heated to the target temperature of room temperature. During the heating process, the temperature difference between the cold hydrazine and the cold stage is greater than 150°C.

[0017] The method described in this invention is applied to the preparation and observation of material samples that are highly sensitive to temperature, electron beams, or ion beams, including lithium battery components, metal-organic framework materials, perovskite materials, or biological samples.

[0018] Compared with the prior art, the present invention has the following advantages: 1. Effectively prevents sample contamination: The cold stage of this invention, also known as a hot-cold stage, maintains deep cooling of the cold hydrazine throughout the heating process (keeping the middle of the first inlet pipe constantly immersed in liquid nitrogen within the liquid nitrogen Dewar flask, with the nitrogen in the first inlet pipe cooling down through heat exchange with the liquid nitrogen), while simultaneously allowing the cold stage to heat up rapidly and independently, creating and maintaining a significant temperature gradient (temperature difference) between the two. This ensures that any volatile contaminants are preferentially captured by the cooler cold hydrazine, rather than the sample, thus guaranteeing the cleanliness of the sample surface.

[0019] 2. Completely eliminate gas path blockage: By continuously purging the gas path of the cold platform with dry, room-temperature nitrogen, the internal pressure of the pipeline is always kept positive and dry, effectively preventing the backflow of external humid air and fundamentally avoiding the occurrence of water vapor condensation and ice blockage.

[0020] 3. Improved Equipment Reliability and Experimental Efficiency: The device of this invention has a simple structure and low modification cost, yet it can significantly improve the operational reliability of the equipment and the success rate of experiments. Simultaneously, because the cold stage can heat up safely and quickly, the experimental cycle is shortened, thus improving work efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a device for preventing contamination and blockage in a scanning electron microscope cold stage system (i.e., a device modified compared to the prior art gas path); Figure 2This is a scanned image showing contaminants (circled in red) on the sample surface before the gas path modification and after heating. Figure 3 This is a scanned image showing that the sample surface was uncontaminated after the system was heated in Example 1 following the modification of the gas path according to the present invention.

[0022] Explanation of reference numerals in the attached figures: 1. Liquid nitrogen Dewar jar; 2. Ambient temperature nitrogen source; 3. First branch pipeline; 4. Second branch pipeline; 5. Cold stage flow valve; 6. Cold hydrazine flow valve; 7. Branch ambient temperature nitrogen control valve; 8. Ambient temperature nitrogen branch; 9. T-connector; 10. Cold stage; 11. Cold hydrazine; 12. Electron gun pole piece; 13. Ion gun; 14. Nitrogen outlet pipe; 15. First inlet pipe. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0024] A device for preventing contamination and clogging in a scanning electron microscope cold stage system, such as... Figure 1 As shown, it includes a vacuum chamber and a cold stage 10, a cold hydrazine 11, an electron gun pole piece 12 and an ion gun 13 disposed in the vacuum chamber. It also includes a main cryogenic gas path system and a normal temperature nitrogen branch 8 with a branch normal temperature nitrogen control valve 7.

[0025] The main cryogenic gas path system includes a liquid nitrogen Dewar 1 and a first inlet pipe 15. Inert gas is introduced into the inlet end of the first inlet pipe 15. The middle part of the first inlet pipe 15 can be moved up and down into the liquid nitrogen Dewar 1. The outlet end of the first inlet pipe 15 is divided into two paths. The first path is connected to the gas inlet of the cold hydrazine 11 through the first branch pipe 3 equipped with a cold hydrazine flow valve 6. The second path is connected to the gas inlet of the cold stage 10 through the second branch pipe 4 equipped with a cold stage flow valve 5.

[0026] The inlet of the ambient temperature nitrogen branch 8 is connected to the ambient temperature nitrogen source 2, and its outlet is connected to the second branch pipeline 4 through a three-way connector 9.

[0027] The inlet end of the first inlet pipe 15 is connected to the ambient temperature nitrogen source 2. The ambient temperature nitrogen source 2 is a nitrogen cylinder. The gas outlets of the cold stage 10 and the cold hydrazine 11 are respectively connected to the nitrogen outlet pipes 14, and both nitrogen outlet pipes 14 extend to the outside of the vacuum chamber.

[0028] like Figure 1As shown, the device of this invention mainly includes a main cryogenic gas circuit system and a room-temperature nitrogen branch circuit. The main cryogenic gas circuit system includes a first branch pipe 3 and a second branch pipe 4. A first inlet pipe 15 is inserted into a liquid nitrogen Dewar jar 1. The outlet of the first inlet pipe 15 splits into two paths: the first path connects to the first branch pipe 3, which leads to a cold hydrazine 11; the second path connects to the second branch pipe 4, which leads to a cold platform 10. A flow valve 5 is installed on the second branch pipe 4. The room-temperature nitrogen branch circuit 8 is led out from the room-temperature nitrogen source 2 and connected to the second branch pipe 4 via a three-way connector 9. A branch room-temperature nitrogen control valve 7 is installed on the room-temperature nitrogen branch circuit 8.

[0029] The working process of the device of the present invention is as follows: 1. Normal cooling / low temperature maintenance stage: The normal temperature nitrogen control valve 7 of the branch is closed, and the corresponding flow valves on the first branch pipeline 3 and the second branch pipeline 4 are opened. Low temperature nitrogen is supplied from the liquid nitrogen Dewar 1 to the cold hydrazine 11 and the cold stage 10 simultaneously through the main low temperature gas circuit system, so that the entire system is in a low temperature state.

[0030] 2. System heating stage: 2.1 Maintaining the low temperature of the cold trap: The first branch pipe 3 is always kept unobstructed, and the cold trap 11 continuously receives low-temperature nitrogen gas to maintain its trapping capacity.

[0031] 2.2 Switching the cold stage gas path: Close the cold stage flow valve 5 on the second branch line 4 to cut off the flow of low-temperature nitrogen to the cold stage 10. At the same time, open the branch line ambient temperature nitrogen control valve 7 to allow dry ambient temperature nitrogen to enter the second branch line 4 to purge the cold stage gas path.

[0032] 2.3 Activate the heating function: Turn on the built-in heating mode of the cold stage 10. Under the protection of nitrogen at room temperature, the cold stage 10 heats up rapidly. At this time, the cold trap 11 maintains an ultra-low temperature (e.g., -192℃), creating a huge temperature difference with the rapidly heating cold stage 10, and the contaminants are effectively locked on the cold trap.

[0033] End of heating phase: After the cold stage 10 reaches room temperature, close the branch room temperature nitrogen control valve 7 to stop the supply of room temperature nitrogen. Extend the middle part of the first inlet pipe 15 above the liquid nitrogen level in the liquid nitrogen Dewar jar, or remove the first inlet pipe 15 from the liquid nitrogen Dewar jar 1 to allow room temperature nitrogen to enter the first branch pipe 3, allowing the cold hydrazine 11 to slowly heat up to return to room temperature.

[0034] Example 1: In a dual-beam system (FEI Helios CX5), a transparent thin film of lithium was extracted from a lithium metal battery electrode for transmission electron microscopy (TEM) observation using cryogenic FIB technology.

[0035] The lithium metal battery was disassembled in a glove box, and the necessary components were attached to the cryogenic sample stage to complete sample preparation. The sample was then transferred to the vacuum chamber of the dual-beam system (FEI Helios CX5) via an argon gas transfer system. Before the system cooled down, 2 μm thick platinum layers were deposited as protective layers for the sample under both electron and ion beams.

[0036] The system was cooled by closing the branch room-temperature nitrogen control valve 7 and opening the cold stage flow valve 5 and the cold hydrazine flow valve 6, bringing the temperature of the cold stage 10 to -160℃ and the temperature of the cold hydrazine 11 to -192℃. After the temperature stabilized, the lithium metal sample was subjected to FIB processing using an ion beam emitted from the ion gun 13 at low temperatures. Large pieces of material were rapidly removed at 30kV and 9.3nA for rough processing and grooving of the sample. The current was then gradually reduced to 2.5nA-0.23nA to trim the sample. After removing the sample, fine thinning and polishing were performed at low temperatures, with the current ranging from 2.5nA to 24pA, decreasing progressively to obtain a clean, undamaged thin area. The low-temperature environment effectively suppressed the irradiation damage of the active lithium metal by the electron / ion beam and prevented the volatilization of electrolytes and other components, ultimately successfully preparing a complete TEM sheet containing original interface information.

[0037] After FIB processing, the system needs to be heated to room temperature to remove the sample. Following the traditional heating method, the heating mode of the cold stage 10 is first activated, putting the cold stage in a heated state. The first inlet 15 is removed from the liquid nitrogen Dewar flask 1, and nitrogen is continuously purged at room temperature for a period of time. Simultaneously, the cold hydrazine 11 begins to heat up, and the temperature difference between it and the cold stage 10 gradually decreases. After the system returns to room temperature, obvious contaminants (such as...) will adhere to the sample surface. Figure 2 (As shown in red). The scanning image of the final sample obtained from FIB processing using traditional heating methods is as follows: Figure 2 As shown.

[0038] After the gas path is modified according to this invention, and after FIB processing is completed, it is done in accordance with Figure 1The device described above operates as follows to heat the system: The first branch pipe 3 and its cold hydrazine flow valve 6 remain open at all times. The cold trap 11 continuously receives cryogenic nitrogen from the liquid nitrogen Dewar 1 to cool the first inlet pipe 15, maintaining its ultra-low temperature trapping capability of approximately -192°C, serving as a "cold spot" within the vacuum chamber. The cold stage flow valve 5 on the second branch pipe 4 is closed, cutting off the flow of cryogenic nitrogen to the cold stage 10. Simultaneously, the branch ambient temperature nitrogen control valve 7 is immediately opened, allowing dry ambient temperature nitrogen to enter the second branch pipe 4 through the ambient temperature nitrogen branch 8. This airflow continuously purges the cold stage gas path, maintaining positive pressure in the pipeline and preventing condensation blockage caused by backflow of external moisture. The heating mode of the cold stage 10 is activated. Under the purging and protection of dry ambient temperature nitrogen, the cold stage 10 and the lithium battery TEM sheet on it begin to heat up rapidly and uniformly. During this process, a huge temperature difference of over 150°C is formed between the deep cryogenic cold trap 11 and the rapidly heating cold stage 10. This temperature difference ensures that any potentially volatile contaminants within the chamber, such as water vapor and oil vapor, will preferentially condense on the cooler surface of the cold trap 11, rather than on the relatively warmer sample surface, thus perfectly protecting the cleanliness of the lithium battery wafer interface. Once the temperature of the cold stage 10 is confirmed to have reached the set room temperature of 28°C, the branch room temperature nitrogen control valve 7 is closed, stopping the room temperature nitrogen supply. Subsequently, the first inlet pipe 15 of the main cryogenic gas path can be removed from the liquid nitrogen Dewar flask 1, allowing room temperature nitrogen to enter the first branch pipe 3, slowly raising the temperature of the cold hydrazine 11 to room temperature. At this point, the system has completely returned to room temperature, and the sample chamber can be safely opened to remove the uncontaminated, structurally intact lithium battery TEM wafer for subsequent high-resolution TEM analysis. Figure 1 The heating method after modifying the gas path of the apparatus shown, and the scanned image of the final sample obtained from FIB processing are shown below. Figure 3 As shown.

[0039] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A device for preventing contamination and clogging in a scanning electron microscope cold stage system, comprising a vacuum chamber and a cold stage (10), a cold hydrazine (11), an electron gun pole piece (12), and an ion gun (13) disposed within the vacuum chamber, characterized in that, It also includes the main cryogenic gas circuit system and the ambient temperature nitrogen branch (8) with a branch ambient temperature nitrogen control valve (7); The main cryogenic gas path system includes a liquid nitrogen Dewar tank (1) and a first inlet pipe (15). Inert gas is introduced into the inlet end of the first inlet pipe (15). The middle part of the first inlet pipe (15) can be moved up and down into the liquid nitrogen Dewar tank (1). The outlet end of the first inlet pipe (15) is divided into two paths. The first path is connected to the gas inlet of the cold hydrazine (11) through the first branch pipe (3) with the cold hydrazine flow valve (6). The second path is connected to the gas inlet of the cold stage (10) through the second branch pipe (4) with the cold stage flow valve (5). The inlet of the ambient temperature nitrogen branch (8) is connected to the ambient temperature nitrogen source (2), and its outlet is connected to the second branch pipeline (4) through a three-way connector (9).

2. The device for preventing contamination and clogging in a scanning electron microscope cold stage system according to claim 1, characterized in that, The inlet end of the first air inlet pipe (15) is connected to a normal temperature nitrogen source (2).

3. The device for preventing contamination and clogging in a scanning electron microscope cold stage system according to claim 2, characterized in that, (2) The nitrogen source at room temperature is a nitrogen cylinder.

4. The device for preventing contamination and clogging in a scanning electron microscope cold stage system according to claim 1, characterized in that, The gas outlets of the cold stage (10) and the cold hydrazine (11) are respectively connected to the nitrogen gas outlet pipe (14), and both nitrogen gas outlet pipes (14) extend to the outside of the vacuum chamber.

5. A method for preventing contamination and clogging in a scanning electron microscope cold stage system based on the apparatus of claim 1, characterized in that, Includes the following steps: S1 Normal cooling / low temperature holding stage: The branch normal temperature nitrogen control valve (7) is closed, the middle part of the first air inlet pipe (15) is inserted into the liquid nitrogen in the liquid nitrogen Dewar tank (1), the air inlet end of the first air inlet pipe (15) is introduced into the normal temperature nitrogen, the normal temperature nitrogen and the liquid nitrogen in the liquid nitrogen Dewar tank (1) exchange heat to form low temperature nitrogen, the corresponding flow valves on the first branch pipe (3) and the second branch pipe (4) are opened, the low temperature nitrogen is discharged from the liquid nitrogen Dewar tank (1) and simultaneously supplied to the cold hydrazine (11) and the cold platform (10) to keep the whole system in a low temperature state; S2 system heating phase: S2.1 Maintaining the low temperature of the cold trap: The first branch pipe (3) is always kept unobstructed, and the cold trap (11) continuously obtains low temperature nitrogen gas to maintain its trapping capacity; S2.2 Switching the cold stage gas path: Close the cold stage flow valve (5) on the second branch pipeline (4) to cut off the low-temperature nitrogen flowing to the cold stage (10); at the same time, open the branch normal temperature nitrogen control valve (7) to allow dry normal temperature nitrogen to enter the second branch pipeline (4) to purge the gas path of the cold stage (10) and maintain the pipeline with dry normal temperature nitrogen passing through. S2.3 Start heating function: Turn on the heating mode of the cold table (10) so that it can be heated up quickly under the protection of nitrogen at room temperature; S2.4 Stop heating: After the cold stage (10) is heated to the target temperature, close the branch room temperature nitrogen control valve (7), adjust the insertion depth of the middle part of the first air inlet pipe (15) so that it is above the liquid nitrogen liquid surface in the liquid nitrogen Dewar tank (1), stop supplying low temperature nitrogen to the cold trap (11), and change to room temperature nitrogen to allow the cold trap (11) to slowly heat up to room temperature.

6. The method according to claim 5, characterized in that, In step S1, the temperature difference between the cold hydrazine (11) and the cold platform (10) is controlled at 30-40℃, the temperature of the cold hydrazine (11) is lower than the temperature of the cold platform (10), and the temperature of the cold hydrazine (11) is maintained at -192℃±10℃.

7. The method according to claim 5, characterized in that, In step S2.4, the cold stage (10) is heated to the target temperature of room temperature. During the heating process, the temperature difference between the cold hydrazine (11) and the cold stage (10) is greater than 150°C.

8. The method according to claim 5, characterized in that, The method is applied to the preparation and observation of material samples that are highly sensitive to temperature, electron beams, or ion beams, including lithium battery components, metal-organic framework materials, perovskite materials, or biological samples.

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