Scanning electron microscope in-situ microcell charge neutralization system and method

Abstract

The invention relates to the technical field of scanning electron microscopes, in particular to a scanning electron microscope in-situ microcell charge neutralization system and method, and the system comprises an initial verification module, an adjustment module, an execution module and a reset verification module, the adjusting module determines the charge level of a sample through low-beam pre-scanning, selects working gas according to the type of the sample and generates an initial parameter; performing micro-area gas injection of the execution module to form a gas mass, performing electron beam bombardment ionization to generate positive ions, neutralizing redundant electrons of a sample, and meanwhile, regulating and controlling the flow, the gas needle position and the beam current in real time; reset verification guarantees equipment safety and data integrity. According to the system, the electron microscope does not need to be transformed, nondestructive and high-resolution imaging under high vacuum is realized, the system is adaptive to various samples, and the application range of the scanning electron microscope is expanded.

Description

Technical Field

[0001] This invention relates to the field of scanning electron microscopy, and more specifically, to a scanning electron microscope in-situ micro-area charge neutralization system and method. Background Technology

[0002] Scanning electron microscopy (SEM), with its nanoscale high-resolution imaging capabilities, has become a core tool for microscopic morphology observation and composition analysis in various fields such as life sciences, materials science, and semiconductor research and development, providing key technical support for basic research and industrial testing. However, the electron optical imaging principle of SEM has stringent requirements on the conductivity of the sample. When observing non-conductive or weakly conductive samples such as biological tissues, polymers, and ceramics, the incident electrons cannot be conducted away in time after interacting with the sample surface, easily accumulating on the sample surface and forming a charging effect. This directly leads to problems such as bright spot drift, edge distortion, and signal fluctuations in imaging, seriously affecting the accuracy of the analytical results.

[0003] The lack of effective conductive paths on the sample surface prevents electrons injected by the incident electron beam from dissipating quickly. This accumulation creates a localized electric field, which interferes with the focusing accuracy of the incident electron beam and affects the normal detection and transmission of secondary and backscattered electron signals. This is particularly problematic for biological samples, which are primarily composed of insulating biomolecules such as proteins and nucleic acids, naturally lacking conductivity. Furthermore, the significant differences in structure and composition among different biological samples further exacerbate the complexity and uncontrollability of the charging effect, becoming a core obstacle to the electron microscopy characterization of these samples.

[0004] Existing charge removal methods all have insurmountable limitations: metal coating methods remove charge by depositing a conductive film on the sample surface, but irreversibly damage the original morphology and chemical properties of the sample, failing to meet the needs of in-situ analysis; low-vacuum modes dissipate charge by reducing the vacuum level of the sample chamber, but at the cost of sacrificing imaging resolution and easily introducing imaging artifacts caused by gas molecule scattering. Currently, the industry lacks a mature technology that can simultaneously achieve "non-destructive preservation of sample characteristics, high-resolution imaging, and low equipment consumption." The pain points of "complex sample preparation process, poor imaging quality, and unreliable analysis results" for biological samples have long remained unresolved, severely limiting the application expansion of SEM in the field of non-conductive samples. Summary of the Invention

[0005] In view of this, the present invention proposes an in-situ micro-area charge neutralization system and method for scanning electron microscopy, which aims to solve the problems of bright spots, edge distortion and signal instability in imaging caused by the accumulation of incident electrons when observing non-conductive or weakly conductive samples with scanning electron microscopy.

[0006] In a first aspect, the present invention provides a scanning electron microscope in-situ micro-region charge neutralization system, comprising: an initial verification module configured to perform pressure testing on the airtightness of the gas path system and to detect the interference intensity of the electromagnetic shielding effectiveness; The adjustment module is configured to acquire the charge intensity information of the target sample through low-current pre-scan imaging, select the working gas type, determine the initial gas flow range and the initial position of the gas needle based on the temperature sensitivity identifier, three-dimensional morphology scanning results and experimental characterization requirements of the target sample, determine the initial gas flow range and the initial position of the gas needle, pre-determine whether the safe distance between the initial position of the gas needle and the target sample meets the preset safety threshold, and at the same time verify the compatibility between the current vacuum degree and the initial gas flow, and generate a personalized initial parameter scheme adapted to the characteristics of the target sample. The execution module is configured to locally introduce the working gas into the observation area of ​​the target sample to form a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is then bombarded by the incident electron beam of the scanning electron microscope to ionize it and generate positive ions. The positive ions are deposited on the surface of the target sample and undergo a charge neutralization reaction with the excess electrons accumulated on the surface of the target sample. The target sample surface charge density data and scanning electron microscope imaging quality parameters are collected in real time, and the gas flow rate, the XZ axis position of the gas needle, and the electron beam current are dynamically adjusted. The reset verification module is configured to reset the gas needle to a safe position away from the sample stage and internal components of the sample chamber, verify the vacuum recovery status of the sample chamber, and simultaneously verify the integrity of the vacuum curve, charge density curve, flow parameters and imaging images collected during the experiment.

[0007] In some embodiments, when the initial verification module is configured to perform a pressure test on the airtightness of the gas path system and an interference intensity test on the effectiveness of electromagnetic shielding, it includes: Apply air pressure to the air circuit and keep it at a constant temperature for a preset time, and monitor the pressure decay in real time through a pressure sensor; When the pressure attenuation value is less than or equal to the preset pressure attenuation threshold, and the pressure application results for three consecutive times all meet the attenuation requirement, the gas path is deemed to be sealed as qualified. Otherwise, the gas path is deemed to be unqualified for sealing.

[0008] In some embodiments, when the initial verification module is configured to perform a pressure test on the airtightness of the gas path system and to detect the interference intensity of the electromagnetic shielding effectiveness, it further includes: The electromagnetic interference intensity at the outlet of the air needle is detected. When the electromagnetic interference intensity is less than or equal to a preset interference threshold, the shielding is deemed qualified. When the electromagnetic interference intensity is greater than the interference threshold, measure the connection resistance between the shielding layer and the grounding terminal of the electron microscope body; When the electromagnetic interference intensity is greater than the interference threshold and the connection resistance is greater than the preset resistance threshold, the grounding terminal is re-polished and the connection is tightened. When the connection resistance is less than or equal to the resistance threshold after the grounding terminal has been re-polished and tightened, the electromagnetic interference intensity is detected again. When the connection resistance is less than or equal to the resistance threshold and the electromagnetic interference intensity is greater than the interference threshold, the gas needle is adjusted in a direction away from the high-voltage component of the electron microscope. When the air needle is adjusted to its limit position and the electromagnetic interference intensity is greater than the interference threshold, the acceleration voltage is reduced.

[0009] In some embodiments, the adjustment module is configured to acquire the charge intensity information of the target sample through low-current pre-scan imaging, select the working gas type, determine the initial gas flow range and the initial position of the gas needle based on the temperature sensitivity identifier, three-dimensional morphology scanning results and experimental characterization requirements of the target sample, pre-determine whether the safety distance between the initial position of the gas needle and the target sample meets a preset safety threshold, and simultaneously verify the compatibility between the current vacuum level and the initial gas flow rate, generating a personalized initial parameter scheme adapted to the characteristics of the target sample, including: The target sample image is obtained by electron beam pre-scanning, and the pixel ratio of the bright spot area in the target sample image is obtained. When the pixel percentage is less than or equal to a preset first pixel percentage threshold, it is a weak charge level; When the pixel percentage is greater than the first pixel percentage threshold and less than or equal to the preset second pixel percentage threshold, it is a medium charge level. When the pixel percentage is greater than the second pixel percentage threshold, it is a strong charge level. The initial gas flow range and initial needle distance are matched according to different charge levels. When the target sample is a semiconductor material, the backscattered electron signal intensity variation coefficient is calculated. When the calculated backscattered electron signal intensity variation coefficient is greater than a preset coefficient threshold, it is determined to be a compositional inhomogeneity, and the gas flow rate is increased based on the corresponding charge level flow rate. When the calculated coefficient of variation of the backscattered electron signal intensity is less than or equal to the coefficient threshold, it is determined that the composition is uniform and the initial flow rate of the corresponding charge level is maintained.

[0010] In some embodiments, the adjustment module is configured to acquire the charge intensity information of the target sample through low-current pre-scan imaging, select the working gas type, determine the initial gas flow range and the initial position of the gas needle based on the temperature sensitivity identifier, three-dimensional morphology scanning results and experimental characterization requirements of the target sample, pre-determine whether the safety distance between the initial position of the gas needle and the target sample meets a preset safety threshold, and simultaneously verify the compatibility between the current vacuum level and the initial gas flow rate. When generating a personalized initial parameter scheme adapted to the characteristics of the target sample, the module further includes: When the target sample is a biological sample, the working gas type is nitrogen; When the target sample is a semiconductor sample, the working gas type is argon. Nitrogen is selected when the target sample is neither a biological sample nor a semiconductor sample.

[0011] In some embodiments, the execution module is configured to locally introduce the working gas into the observation area of ​​the target sample to form a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is then bombarded with an incident electron beam from the scanning electron microscope to ionize it and generate positive ions. These positive ions deposit on the surface of the target sample and neutralize excess electrons accumulated on the surface. Real-time acquisition of the target sample surface charge density data and scanning electron microscope imaging quality parameters, along with dynamic control of the gas flow rate, needle XZ axis position, and electron beam current, includes: The vacuum level of the sample chamber is collected in real time, and the maximum allowable gas flow rate is calculated based on the preset equipment coefficient k according to the scanning electron microscope model. The gas flow rate is controlled during actual operation. When the vacuum level is greater than or equal to a preset first vacuum level threshold, reduce the gas flow rate; When the vacuum level recovers to less than or equal to the preset second vacuum level threshold after the gas flow rate is reduced, it is determined that the flow rate is over the limit, and the adjusted flow rate is maintained. When the vacuum level recovers to a value greater than the second vacuum threshold after the gas flow rate is reduced, the gas path sealing is checked. When the gas path sealing is qualified, the vacuum system pumping speed is checked. When the pumping speed is lower than the preset percentage of the equipment standard value, the vacuum system is restarted and the test is repeated. If the vacuum cannot be restored even with a normal pumping speed, the experiment is suspended.

[0012] In some embodiments, the execution module is configured to locally introduce the working gas into the observation area of ​​the target sample to form a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is then bombarded by an incident electron beam from the scanning electron microscope to ionize it and generate positive ions. These positive ions deposit on the surface of the target sample and neutralize excess electrons accumulated on the surface. Real-time acquisition of surface charge density data and scanning electron microscope imaging quality parameters, along with dynamic control of gas flow rate, needle XZ axis position, and electron beam current, further includes: Set a charge density threshold for the target sample surface. When the charge density of the target sample surface drops to less than or equal to the charge density threshold within a preset time, maintain the current parameter. When the surface charge density of the target sample drops to a value greater than the charge density threshold within a preset time, check whether the electron beam current is within the preset beam current threshold range. When the beam current is less than the beam current threshold range, increase the electron beam current; When the electron beam current is within a preset beam current threshold range, and the surface charge density of the target sample is greater than the charge density threshold, the distance from the center of the gas needle outlet end face to the surface of the sample observation area is reduced.

[0013] In some embodiments, the execution module is configured to locally introduce the working gas into the observation area of ​​the target sample to form a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is then bombarded by an incident electron beam from the scanning electron microscope to ionize it and generate positive ions. These positive ions deposit on the surface of the target sample and neutralize excess electrons accumulated on the surface. Real-time acquisition of surface charge density data and scanning electron microscope imaging quality parameters, along with dynamic control of gas flow rate, needle XZ axis position, and electron beam current, further includes: Calculate the bright spot area and edge distortion rate; When the bright spot area is greater than the preset bright spot area threshold and the edge distortion rate is less than or equal to the preset distortion rate threshold, adjust the X-axis position of the air adjustment needle to move closer to the center region of the bright spot until the bright spot area is less than or equal to the bright spot area threshold. If the number of fine-tuning attempts exceeds the preset number, and the bright spot area exceeds the preset bright spot area threshold, increase the gas flow rate. When the edge distortion rate is greater than the distortion rate threshold and the bright spot area is less than or equal to the bright spot area threshold, reduce the gas flow rate until the distortion rate is less than or equal to the distortion rate threshold. When the gas flow rate is reduced, if the edge distortion rate exceeds the distortion rate threshold, the beam current is reduced. When the bright spot area is greater than the preset bright spot area threshold and the edge distortion rate is greater than the distortion rate threshold, neutralization is immediately paused, the gas passage is closed, and after the vacuum level is restored to the second vacuum level threshold, the initial parameters are reset according to the weak charge level, and the neutralization process is restarted.

[0014] In some embodiments, the execution module is configured to locally introduce the working gas into the observation area of ​​the target sample to form a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is then bombarded by an incident electron beam from the scanning electron microscope to ionize it and generate positive ions. These positive ions deposit on the surface of the target sample and neutralize excess electrons accumulated on the surface. Real-time acquisition of surface charge density data and scanning electron microscope imaging quality parameters, along with dynamic control of gas flow rate, needle XZ axis position, and electron beam current, further includes: After the sample stage is moved to the new observation area, the new height of the sample surface is obtained by the laser displacement sensor, and the change in height is obtained. When the height change is less than or equal to a preset change threshold, the Z-axis position of the fine-tuning needle is consistent with the height change to maintain the original gas flow rate. When the change in height is greater than the change threshold, the maximum allowable flow rate is recalculated. When the deviation between the new flow rate and the original flow rate is less than or equal to the preset deviation threshold, only the Z-axis position of the needle is adjusted. When the deviation between the new flow rate and the original flow rate is greater than the deviation threshold, the gas flow rate is adjusted, and the new area is pre-scanned. When the change in charge intensity after the pre-scan is less than or equal to the preset change threshold, maintain the adjusted flow rate. Otherwise, adjust the gas flow rate; When the distance between the air needle and the sample stage is greater than or equal to the preset distance threshold after the air needle has moved, no position adjustment is required; When the distance between the air needle and the sample stage is less than the distance threshold after the air needle moves, the Z-axis of the sample stage is raised. When the sample stage reaches its maximum stroke, the Z-axis of the air needle is lowered until the distance between the air needle and the sample stage is greater than or equal to the distance threshold.

[0015] Secondly, the present invention provides a method for in-situ charge neutralization in a micro-region using scanning electron microscopy, comprising the following steps: Pressure tests were conducted to assess the airtightness of the gas system, and interference intensity tests were performed to determine the effectiveness of the electromagnetic shielding. The target sample's charge intensity information is obtained through low-current pre-scan imaging. Based on the target sample's temperature sensitivity identifier, three-dimensional morphology scanning results, and experimental characterization requirements, the working gas type is selected, the initial gas flow range and the initial position of the gas needle are determined, and it is pre-judged whether the safe distance between the initial position of the gas needle and the target sample meets the preset safety threshold. At the same time, the compatibility between the current vacuum level and the initial gas flow rate is verified, and a personalized initial parameter scheme adapted to the characteristics of the target sample is generated. The working gas is introduced locally into the observation area of ​​the target sample to form a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is bombarded by the incident electron beam of the scanning electron microscope to ionize it and generate positive ions. The positive ions are deposited on the surface of the target sample and undergo a charge neutralization reaction with the excess electrons accumulated on the surface of the target sample. The surface charge density data of the target sample and the imaging quality parameters of the scanning electron microscope are collected in real time, and the gas flow rate, the XZ axis position of the gas needle and the electron beam current are dynamically adjusted. The gas needle was reset to a safe position away from the sample stage and internal components of the sample chamber. The vacuum recovery status of the sample chamber was verified, and the integrity of the vacuum curve, charge density curve, flow parameters and imaging images collected during the experiment was verified.

[0016] Compared with existing technologies, the advantages of this invention are as follows: The initial verification module performs pressure testing on the gas path sealing and interference intensity detection on the effectiveness of electromagnetic shielding, thus avoiding the risks of gas leakage damaging the high vacuum environment and electromagnetic interference affecting detection accuracy from the source, providing a safe and stable foundation for charge neutralization; The adjustment module obtains sample charge intensity information through low-current pre-scanning, selects the working gas, determines the initial flow rate and gas needle position based on sample type, three-dimensional morphology and other characteristics, and also pre-judges the safe distance between the gas needle and the sample and the matching of vacuum degree and initial flow rate, generating a personalized initial parameter scheme, ensuring the accurate adaptability of charge neutralization, and solving the problem that existing schemes cannot take into account the differences in charge of different samples; The execution module forms a gas cloud that does not disrupt the vacuum through micro-area gas injection, utilizing... Electron beam bombardment ionizes and generates positive ions to neutralize excess electrons in the sample. Simultaneously, the flow rate, XZ axis position of the gas needle, and electron beam current are controlled in real time. This eliminates imaging problems such as bright spots and edge distortion caused by the charge effect at the source, while ensuring nanoscale high resolution in a high vacuum environment. It avoids damage to the sample caused by metal coating methods and resolution loss in low vacuum modes. The reset and calibration module resets the gas needle to a safe position and verifies the vacuum recovery status and experimental data integrity, ensuring the safety of the equipment and sample and the validity of the data. Moreover, the entire system does not require modification of the core structure of the electron microscope, reducing equipment wear and tear. It is also compatible with various types of samples, such as biological samples, semiconductors, and weakly conductive materials, effectively expanding the application range of scanning electron microscopes and completely solving the core pain points of "difficult sample preparation, difficult imaging, and difficult analysis" of non-conductive samples.

[0017] The above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure.

[0018] Other features and aspects of this disclosure will become clearer from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a functional block diagram of the in-situ charge neutralization system for scanning electron microscopes provided in an embodiment of the present invention. Figure 2 This is a flowchart of the in-situ charge neutralization method for scanning electron microscopy provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the in-situ charge neutralization system for scanning electron microscopes provided in an embodiment of the present invention. Detailed Implementation

[0021] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] In the first embodiment of this application, see Figure 1 and Figure 3 As shown, this application provides an in-situ charge neutralization system for scanning electron microscopes, comprising: The initial verification module is configured to perform pressure tests on the airtightness of the gas circuit system and interference intensity tests on the effectiveness of electromagnetic shielding. The adjustment module is configured to acquire the charge intensity information of the target sample through low-current pre-scan imaging, select the working gas type, determine the initial gas flow range and the initial position of the gas needle based on the temperature sensitivity identifier, three-dimensional morphology scanning results and experimental characterization requirements of the target sample, determine the initial gas flow range and the initial position of the gas needle, pre-determine whether the safe distance between the initial position of the gas needle and the target sample meets the preset safety threshold, and at the same time verify the compatibility between the current vacuum degree and the initial gas flow, and generate a personalized initial parameter scheme adapted to the characteristics of the target sample. The execution module is configured to locally introduce the working gas into the observation area of ​​the target sample to form a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is then bombarded by the incident electron beam of the scanning electron microscope to ionize it and generate positive ions. The positive ions are deposited on the surface of the target sample and undergo a charge neutralization reaction with the excess electrons accumulated on the surface of the target sample. The target sample surface charge density data and scanning electron microscope imaging quality parameters are collected in real time, and the gas flow rate, the XZ axis position of the gas needle, and the electron beam current are dynamically adjusted. The reset verification module is configured to reset the gas needle to a safe position away from the sample stage and internal components of the sample chamber, verify the vacuum recovery status of the sample chamber, and simultaneously verify the integrity of the vacuum curve, charge density curve, flow parameters and imaging images collected during the experiment.

[0023] It should be understood that the initial calibration module provides fundamental assurance for system operation. Through gas path sealing and electromagnetic shielding detection, it prevents gas leaks from disrupting the vacuum or electromagnetic interference from affecting detection accuracy. The adjustment module generates personalized parameter schemes based on sample characteristics, ensuring that initial parameters are adapted to the sample's state of charge and experimental requirements. The execution module is the core working unit, eliminating the charging effect at its source through the linkage of gas injection, ionization neutralization, and real-time control. The reset calibration module ensures equipment safety and data integrity after the experiment, providing support for subsequent experiments or data processing. All system modules communicate with the scanning electron microscope (SEM) through standardized interfaces, supporting seamless integration with mainstream SEM models (such as Zeiss Crossbeam 350, Hitachi SU8010, and FEI Quanta 650) without requiring modification of the SEM's core structure. Data transmission between modules uses a high-speed bus protocol with a transmission delay ≤10ms, ensuring rapid response for real-time control. The system has a built-in emergency shutdown procedure. When any module detects a fatal fault (such as a sudden drop in vacuum or gas path rupture), it can immediately cut off the gas path and electron beam, protecting the SEM and sample.

[0024] In some specific embodiments, the initial verification module is configured to perform pressure testing on the airtightness of the gas path system and interference intensity detection on the effectiveness of electromagnetic shielding, including: Apply air pressure to the air circuit and keep it at a constant temperature for a preset time, and monitor the pressure decay in real time through a pressure sensor; When the pressure attenuation value is less than or equal to the preset pressure attenuation threshold, and the pressure application results for three consecutive times all meet the attenuation requirement, the gas path is deemed to be sealed as qualified. Otherwise, the gas path is deemed to be unqualified for sealing.

[0025] It should be understood that the gas path sealing is the key to ensuring the high vacuum environment of the scanning electron microscope. The gas path sealing performance is verified by pressure decay test: apply a constant gas pressure to the gas path and let it stand. If the pressure decay is within the allowable range, it means that there is no gas path leakage and it can meet the subsequent gas injection requirements; if the decay exceeds the standard, the leak point needs to be investigated to avoid gas leakage during the experiment from destroying the vacuum. Preset air pressure: 0.1MPa (industry standard gas circuit sealing test pressure, capable of detecting minute leaks without damaging gas circuit valves and pipelines); Preset time: 5 minutes (sufficient to detect slow leaks, balancing detection accuracy and efficiency); Preset pressure decay threshold: 0.005MPa (based on the pumping speed of the scanning electron microscope vacuum system, this decay amount will not cause the sample chamber vacuum level to exceed the imaging allowable range); Number of repeated pressurization cycles: 3 times (avoiding the randomness of a single test and ensuring stable sealing performance); Test medium: dry air (moisture content ≤10ppm) to avoid moisture residue causing corrosion of the gas path or sample contamination. The gas path includes a main gas path and a backup gas path, and each path must be tested for tightness to ensure that the backup path can be switched in case of a single path failure, thus ensuring experimental continuity. Pressure sensor accuracy: ±0.0001MPa, ensuring accurate detection of pressure decay.

[0026] Leakage handling: If the attenuation exceeds the standard, use the "soap bubble method + flow sensor baseline drift analysis" to locate the leak point (interfaces and valves are high-risk leak locations), repair and re-test the pressure until it meets the standard three times in a row.

[0027] In some specific embodiments, the initial verification module is configured to perform a pressure test on the airtightness of the gas path system and, when performing an interference intensity test on the effectiveness of electromagnetic shielding, further include: The electromagnetic interference intensity at the outlet of the air needle is detected. When the electromagnetic interference intensity is less than or equal to a preset interference threshold, the shielding is deemed qualified. When the electromagnetic interference intensity is greater than the interference threshold, measure the connection resistance between the shielding layer and the grounding terminal of the electron microscope body; When the electromagnetic interference intensity is greater than the interference threshold and the connection resistance is greater than the preset resistance threshold, the grounding terminal is re-polished and the connection is tightened. When the connection resistance is less than or equal to the resistance threshold after the grounding terminal has been re-polished and tightened, the electromagnetic interference intensity is detected again. When the connection resistance is less than or equal to the resistance threshold and the electromagnetic interference intensity is greater than the interference threshold, the gas needle is adjusted in a direction away from the high-voltage component of the electron microscope. When the air needle is adjusted to its limit position and the electromagnetic interference intensity is greater than the interference threshold, the acceleration voltage is reduced.

[0028] It should be understood that the electron beam and high-voltage components inside the scanning electron microscope (SEM) generate electromagnetic radiation. Excessive electromagnetic interference can affect the accuracy of charge density detection and the stability of nitrogen ionization. A step-by-step approach—interference intensity detection, grounding resistance investigation, needle position adjustment, and acceleration voltage reduction—is used to ensure adequate electromagnetic shielding. Preset interference threshold: 5mV (based on the accuracy of the electrostatic probe, interference below this threshold will not affect the charge density measurement error, ensuring an error ≤5%). Preset resistance threshold: 1Ω (when the grounding resistance is ≤1Ω, the interference current can be effectively diverted into the microscope body, reducing the impact of electromagnetic radiation). Needle adjustment distance: ≥5cm (away from the high-voltage components of the microscope; this distance can reduce electromagnetic interference intensity by more than 30%). Acceleration voltage lower limit: 20kV (below this voltage can still meet the basic imaging requirements of most samples, avoiding a significant decrease in resolution due to excessively low voltage).

[0029] Electrostatic probe installation position: 1cm from the outlet end of the gas needle (close to the gas ionization area, which can accurately detect electromagnetic interference in the area).

[0030] Shielding structure: The air needle rod and the drive unit are wrapped with a multi-layer copper foil-polyimide composite shielding layer (thickness ≤50μm), and the air pipeline is plated with nickel alloy. The double shielding improves the anti-interference capability. Testing procedure: First, turn on the high voltage power supply of the electron microscope (accelerating voltage 20-30kV, simulating actual imaging conditions), and then perform interference intensity testing to ensure that the test environment is consistent with the actual working environment. Handling damaged shielding layer: If the shielding layer is found to be damaged during inspection, the entire shielding layer must be replaced. Temporary repairs are not allowed (to avoid localized interference and leakage).

[0031] In some specific embodiments, the adjustment module is configured to acquire the charge intensity information of the target sample through low-current pre-scan imaging, select the working gas type, determine the initial gas flow range and the initial position of the gas needle based on the temperature sensitivity identifier, three-dimensional morphology scanning results and experimental characterization requirements of the target sample, pre-determine whether the safety distance between the initial position of the gas needle and the target sample meets a preset safety threshold, and simultaneously verify the compatibility between the current vacuum level and the initial gas flow rate. When generating a personalized initial parameter scheme adapted to the characteristics of the target sample, the module includes: The target sample image is obtained by electron beam pre-scanning, and the pixel ratio of the bright spot area in the target sample image is obtained. When the pixel percentage is less than or equal to a preset first pixel percentage threshold, it is a weak charge level; When the pixel percentage is greater than the first pixel percentage threshold and less than or equal to the preset second pixel percentage threshold, it is a medium charge level. When the pixel percentage is greater than the second pixel percentage threshold, it is a strong charge level. The initial gas flow range and initial needle distance are matched according to different charge levels. When the target sample is a semiconductor material, the backscattered electron signal intensity variation coefficient is calculated. When the calculated backscattered electron signal intensity variation coefficient is greater than a preset coefficient threshold, it is determined to be a compositional inhomogeneity, and the gas flow rate is increased based on the corresponding charge level flow rate. When the calculated coefficient of variation of the backscattered electron signal intensity is less than or equal to the coefficient threshold, it is determined that the composition is uniform and the initial flow rate of the corresponding charge level is maintained.

[0032] It should be understood that the charge intensity varies significantly among different samples (e.g., thin graphene sheets have a weak charge, while thick polymer blocks have a strong charge). Using fixed parameters would lead to insufficient or excessive neutralization. A low-current pre-scan is used to obtain the bright spot percentage, classify the charge levels, and match the initial parameters. Additional flow rate adjustments are made to account for the compositional uniformity differences in semiconductor samples, ensuring accurate neutralization.

[0033] Electron beam pre-scan parameters: beam current 10pA (low beam current can avoid generating additional charge during pre-scanning and does not affect the original charge state of the sample), scan time 10 seconds (sufficient to obtain a clear image and count the proportion of bright spots). Pixel percentage thresholds: First pixel percentage threshold 3% (weak charge level threshold), second pixel percentage threshold 10% (medium / strong charge level threshold; based on a large number of experimental statistics, this threshold can accurately distinguish the charge intensity of different samples). Charge rating parameters: Weak charge: initial flow rate 0.05-0.1 sccm, needle distance 80-100 μm (weak charge, no need for large flow rate, long distance can avoid excessive gas affecting the vacuum). Sino-Dutch Electric: Initial flow rate 0.1-0.3 sccm, needle distance 60-80 μm (balancing neutralization efficiency and vacuum stability). Strong charging: initial flow rate 0.3-0.5 sccm, needle distance 50-60 μm (close distance, high flow rate, rapid neutralization of a large number of accumulated electrons); Coefficient threshold: 15% (When the coefficient of variation of backscattered electron signal intensity is >15%, it indicates that the semiconductor sample is not uniform in composition and is prone to localized charge accumulation, so the flux enhancement and neutralization effect needs to be improved). Flow rate adjustment range: 10%-20% (based on experimental verification, this range can effectively cope with local charging caused by uneven composition and will not cause vacuum fluctuations).

[0034] Bright spot percentage statistics: The image analysis software automatically identifies pixels with a gray value > 240 (bright spot areas) in the image and calculates their proportion of the total pixels. Backscattered electron signal analysis: Energy dispersive spectroscopy (EDS) was used for analysis. The uniformity of the components was reflected by the coefficient of variation of the signal intensity. The coefficient of variation = (standard deviation of signal intensity / mean of signal intensity) × 100%. Non-semiconductor sample processing: No need to analyze backscattered electron signals, directly match initial parameters according to charge level, simplifying the operation process; Parameter storage: The system automatically records the charge level and corresponding parameters of different samples to form a historical database, which can be quickly retrieved for similar samples in the future.

[0035] In some specific embodiments, the adjustment module is configured to acquire the charge intensity information of the target sample through low-current pre-scan imaging, select the working gas type, determine the initial gas flow range and the initial position of the gas needle based on the temperature sensitivity identifier, three-dimensional morphology scanning results and experimental characterization requirements of the target sample, pre-determine whether the safety distance between the initial position of the gas needle and the target sample meets a preset safety threshold, and simultaneously verify the compatibility between the current vacuum level and the initial gas flow rate. When generating a personalized initial parameter scheme adapted to the characteristics of the target sample, the module further includes: When the target sample is a biological sample, the working gas type is nitrogen; When the target sample is a semiconductor sample, the working gas type is argon. Nitrogen is selected when the target sample is neither a biological sample nor a semiconductor sample.

[0036] It should be understood that the selection of working gas should take into account three major factors: ionization efficiency, sample compatibility, and cost. Biological samples need to avoid ion contamination, semiconductor samples need to avoid residual impurities, and non-special samples should prioritize low-cost, high-ionization-efficiency gases.

[0037] Gas purity requirements: Nitrogen purity ≥ 99.999% (non-toxic, high ionization efficiency, can quickly generate positive ions, and low cost), Argon purity ≥ 99.9995% (stronger inertness, no residual impurities after ionization, avoiding contamination of semiconductor samples). For non-biological and non-semiconductor samples, such as common metal oxides and ceramic materials, nitrogen is chosen because nitrogen has an ionization efficiency that is more than 20% higher than that of argon, and its cost is only 1 / 3 of that of argon, which can reduce experimental costs. Special sample verification: If the sample type is uncertain (such as a new composite material), a pre-test can be performed in a non-critical area at the edge of the sample. Nitrogen and argon are injected for 30 seconds each, and the sample morphology is observed to see if there are any changes (such as cracks or deformation). Energy dispersive spectroscopy is used to detect whether any new elements have been added to the surface. Gases without abnormalities are selected. Gas storage and supply: High-pressure gas cylinders are used to store gas, and the output pressure is stabilized at 0.5MPa by a pressure reducing valve to avoid unstable flow caused by pressure fluctuations.

[0038] In some specific embodiments, the execution module is configured to locally introduce the working gas into the observation area of ​​the target sample, forming a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is then bombarded by the incident electron beam of the scanning electron microscope, causing it to ionize and generate positive ions. These positive ions deposit on the surface of the target sample and undergo a charge neutralization reaction with excess electrons accumulated on the surface. Real-time acquisition of the target sample surface charge density data and scanning electron microscope imaging quality parameters, along with dynamic control of the gas flow rate, the XZ axis position of the gas needle, and the electron beam current, includes: The vacuum level of the sample chamber is collected in real time, and the maximum allowable gas flow rate is calculated based on the preset equipment coefficient k according to the scanning electron microscope model. The gas flow rate is controlled during actual operation. When the vacuum level is greater than or equal to a preset first vacuum level threshold, reduce the gas flow rate; When the vacuum level recovers to less than or equal to the preset second vacuum level threshold after the gas flow rate is reduced, it is determined that the flow rate is over the limit, and the adjusted flow rate is maintained. When the vacuum level recovers to a value greater than the second vacuum threshold after the gas flow rate is reduced, the gas path sealing is checked. When the gas path sealing is qualified, the vacuum system pumping speed is checked. When the pumping speed is lower than the preset percentage of the equipment standard value, the vacuum system is restarted and the test is repeated. If the vacuum cannot be restored even with a normal pumping speed, the experiment is suspended.

[0039] It should be understood that scanning electron microscopy imaging requires a high vacuum environment (typically ≤10). -3 Excessive gas flow can lead to a decrease in vacuum, affecting imaging quality. By monitoring the vacuum level in real time and dynamically adjusting the flow rate, while simultaneously investigating the root causes of abnormal vacuum levels (excessive flow, gas path leakage, vacuum system malfunction), a balance between the vacuum environment and the neutralization effect can be ensured.

[0040] Equipment coefficient k: Different models of scanning electron microscopes have different vacuum system pumping speeds, and coefficient k needs to be determined according to the equipment calibration. ZeissCrossbeam350: k=0.001sccm / Pa (high pumping speed, large maximum allowable flow rate); Hitachi SU8010: k=0.0008sccm / Pa (medium pumping speed, slightly lower allowable flow rate); FEIQuanta650: k = 0.0009 sccm / Pa; The maximum allowable flow rate is Q_max = k × P_current (P_current is the current vacuum level), and the actual flow rate is controlled at Q_max × 0.8 (with a 20% safety margin to avoid a sudden drop in vacuum level). First vacuum threshold: 10 -2 Pa (If the flow rate exceeds this threshold, problems such as blurred imaging and weakened signal will occur, and the flow rate needs to be adjusted immediately). Second vacuum threshold: 10 -3 Pa (lower limit of the optimal vacuum range for scanning electron microscopy imaging; recovery to this threshold indicates a stable vacuum environment). Preset percentage: 80% (When the vacuum system pumping speed is lower than 80% of the standard value, it indicates that the pumping speed is insufficient and the system needs to be restarted to restore the pumping speed).

[0041] Vacuum degree monitoring accuracy: 10 -5 Pa (using a capacitive vacuum gauge to ensure the accuracy of vacuum measurement); Flow rate adjustment step size: 0.05 sccm (small adjustments made multiple times to avoid sudden changes in flow rate that could cause fluctuations in vacuum). Gas circuit sealing test: When the vacuum is abnormal, test the gas circuit according to the pressure test method above (0.1MPa gas pressure, stand for 5 minutes). If the attenuation value is ≤0.005MPa, the sealing is deemed qualified. Vacuum system pumping speed test: If the pumping speed does not recover, the pumping speed can be detected by the built-in pumping speed monitoring function of the electron microscope or by an external flow meter. If the pumping speed does not recover, the molecular pump and mechanical pump should be checked for faults (such as insufficient speed of the molecular pump or low oil level of the mechanical pump).

[0042] In some specific embodiments, the execution module is configured to locally introduce the working gas into the observation area of ​​the target sample, forming a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is then bombarded by the incident electron beam of the scanning electron microscope, causing it to ionize and generate positive ions. These positive ions deposit on the surface of the target sample and undergo a charge neutralization reaction with excess electrons accumulated on the surface. Real-time acquisition of the target sample surface charge density data and scanning electron microscope imaging quality parameters, along with dynamic control of the gas flow rate, the XZ axis position of the gas needle, and the electron beam current, further includes: Set a charge density threshold for the target sample surface. When the charge density of the target sample surface drops to less than or equal to the charge density threshold within a preset time, maintain the current parameter. When the surface charge density of the target sample drops to a value greater than the charge density threshold within a preset time, check whether the electron beam current is within the preset beam current threshold range. When the beam current is less than the beam current threshold range, increase the electron beam current; When the electron beam current is within a preset beam current threshold range, and the surface charge density of the target sample is greater than the charge density threshold, the distance from the center of the gas needle outlet end face to the surface of the sample observation area is reduced.

[0043] It should be understood that charge density is the core indicator reflecting the effectiveness of eliminating the charge effect. By monitoring the charge density, adjusting the electron beam current (ionization energy) and the distance between the needles (positive ion deposition efficiency), it is ensured that the charge density is reduced to the target threshold within a preset time, thereby achieving effective neutralization.

[0044] Charge density threshold: 10 -5 C / m² (below this threshold, the charge effect will not interfere with electron beam focusing and signal detection, and the imaging quality is stable). Preset time: 30 seconds (based on the ionization efficiency of nitrogen / argon, most samples can be neutralized within 30 seconds, avoiding excessive neutralization time that could affect experimental efficiency). Beam current threshold range: 20-50 pA (when the beam current is <20 pA, the energy of the ionized gas is insufficient and the amount of positive ions generated is small; when the beam current is >50 pA, it will cause the sample surface to heat up, which may damage biological samples or thermosensitive materials). Gas needle distance adjustment step: 5μm (small adjustments can precisely control positive ion deposition efficiency, avoiding collisions with the sample due to being too close or decreases in neutralization efficiency due to being too far away); Lower limit of gas needle distance: 50μm (this distance can avoid collision between the gas needle and the sample surface protrusion, while ensuring that positive ions can be effectively deposited on the sample surface).

[0045] Charge density acquisition: Data is acquired using a miniature electrostatic induction probe (diameter ≤1mm, detection distance 100-200μm) at a frequency of 1 Hz. The data is then amplified by a preamplifier (gain 10). 4 The data is transmitted to the control system via an A / D converter (sampling rate 1kHz). Beam adjustment method: The beam current is increased in increments of 5pA. After each increase, wait 5 seconds before monitoring the charge density to avoid misjudgment due to unstable ionization efficiency after beam current changes. Definition of air needle distance: The vertical distance from the center of the air needle outlet end face to the surface of the sample observation area, which is monitored in real time by a laser displacement sensor (measurement accuracy ±2nm); Handling extreme cases: If the needle distance has been reduced to 50μm and the beam current has reached 50pA, but the charge density still does not meet the standard, it is determined that the gas type is mismatched. Switch to the backup gas and retest.

[0046] In some specific embodiments, the execution module is configured to locally introduce the working gas into the observation area of ​​the target sample, forming a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is then bombarded by the incident electron beam of the scanning electron microscope, causing it to ionize and generate positive ions. These positive ions deposit on the surface of the target sample and undergo a charge neutralization reaction with excess electrons accumulated on the surface. Real-time acquisition of the target sample surface charge density data and scanning electron microscope imaging quality parameters, along with dynamic control of the gas flow rate, the XZ axis position of the gas needle, and the electron beam current, further includes: Calculate the bright spot area and edge distortion rate; When the bright spot area is greater than the preset bright spot area threshold and the edge distortion rate is less than or equal to the preset distortion rate threshold, adjust the X-axis position of the air adjustment needle to move closer to the center region of the bright spot until the bright spot area is less than or equal to the bright spot area threshold. If the number of fine-tuning attempts exceeds the preset number, and the bright spot area exceeds the preset bright spot area threshold, increase the gas flow rate. When the edge distortion rate is greater than the distortion rate threshold and the bright spot area is less than or equal to the bright spot area threshold, reduce the gas flow rate until the distortion rate is less than or equal to the distortion rate threshold. When the gas flow rate is reduced, if the edge distortion rate exceeds the distortion rate threshold, the beam current is reduced. When the bright spot area is greater than the preset bright spot area threshold and the edge distortion rate is greater than the distortion rate threshold, neutralization is immediately paused, the gas passage is closed, and after the vacuum level is restored to the second vacuum level threshold, the initial parameters are reset according to the weak charge level, and the neutralization process is restarted.

[0047] It should be understood that the imaging quality directly reflects the neutralization effect. By analyzing the bright spot area (local charge index) and the edge distortion rate (electron beam interference index), the position of the gas needle (to solve local charge), the gas flow rate (to solve electron beam scattering), and the electron beam current (to solve excessive interference) are adjusted in a targeted manner to form a closed loop of "imaging quality - parameter adjustment" to ensure clear and distortion-free imaging.

[0048] Bright spot area threshold: 1% (when the bright spot area is greater than 1%, it indicates that the local charge has not been completely eliminated, affecting the observation details); Edge distortion rate threshold: 5% (when the edge distortion rate is >5%, it indicates that the electron beam is interfered with and the sample morphology is not accurately restored). Preset number of attempts: 5 (If the target is still not met after 5 fine-tuning of the needle position, it means that adjusting the position alone cannot solve the problem, and it is necessary to increase the flow rate to enhance neutralization). Flow rate adjustment step: 0.03 sccm (small adjustments to the flow rate to avoid vacuum fluctuations); Beam current limit: 10pA (When the beam current is below 10pA, the imaging resolution will drop significantly, and the minimum beam current must be reserved to ensure the basic resolution).

[0049] Image acquisition: An image is acquired every 10 seconds, and the bright spot area (the proportion of pixels with a gray value > 240) and edge distortion rate (the average deviation between the actual edge and the fitted straight line) are automatically calculated by image analysis software. X-axis adjustment of the gas needle: move closer to the center of the bright spot, with a step size of 3μm / time. After each adjustment, wait 3 seconds before acquiring the image to ensure that positive ions can accurately cover the charged area. Handling of dual out-of-range indicators: When the bright spot area is greater than 1% and the edge distortion rate is greater than 5%, it indicates that the charging effect and electron beam interference exist simultaneously. Neutralization should be suspended, the gas passage should be closed, and the vacuum level should be allowed to recover to 10. -3 After Pa, reset the initial parameters according to the weak charge level (to avoid interference caused by excessive initial flow) and restart the neutralization process; If the sample still exceeds the limit after restarting, it is determined that the sample's charge effect exceeds the neutralization capacity of the system. The user is advised to replace the sample (e.g., reduce the sample thickness) or adjust the electron microscope imaging parameters (e.g., reduce the accelerating voltage to 15kV).

[0050] In some specific embodiments, the execution module is configured to locally introduce the working gas into the observation area of ​​the target sample, forming a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is then bombarded by the incident electron beam of the scanning electron microscope, causing it to ionize and generate positive ions. These positive ions deposit on the surface of the target sample and undergo a charge neutralization reaction with excess electrons accumulated on the surface. Real-time acquisition of the target sample surface charge density data and scanning electron microscope imaging quality parameters, along with dynamic control of the gas flow rate, the XZ axis position of the gas needle, and the electron beam current, further includes: After the sample stage is moved to the new observation area, the new height of the sample surface is obtained by the laser displacement sensor, and the change in height is obtained. When the height change is less than or equal to a preset change threshold, the Z-axis position of the fine-tuning needle is consistent with the height change to maintain the original gas flow rate. When the change in height is greater than the change threshold, the maximum allowable flow rate is recalculated. When the deviation between the new flow rate and the original flow rate is less than or equal to the preset deviation threshold, only the Z-axis position of the needle is adjusted. When the deviation between the new flow rate and the original flow rate is greater than the deviation threshold, the gas flow rate is adjusted, and the new area is pre-scanned. When the change in charge intensity after the pre-scan is less than or equal to the preset change threshold, maintain the adjusted flow rate. Otherwise, adjust the gas flow rate; When the distance between the air needle and the sample stage is greater than or equal to the preset distance threshold after the air needle has moved, no position adjustment is required; When the distance between the air needle and the sample stage is less than the distance threshold after the air needle moves, the Z-axis of the sample stage is raised. When the sample stage reaches its maximum stroke, the Z-axis of the air needle is lowered until the distance between the air needle and the sample stage is greater than or equal to the distance threshold.

[0051] It should be understood that after the sample stage is moved, the height and state of charge of the new observation area may change. If the parameters remain unchanged, it may lead to a decrease in neutralization effect or a risk of collision. By adjusting the position of the gas needle (to adapt to changes in height) and the flow rate (to adapt to changes in state of charge), while avoiding the risk of collision, the neutralization effect and safety can be ensured after the sample stage is moved.

[0052] Change threshold: 10μm (when the height change is ≤10μm, the impact on positive ion deposition efficiency is minimal, and no flow rate adjustment is required). Deviation threshold: 0.1 sccm (when the flow deviation is ≤0.1 sccm, the neutralization effect is not significantly changed, and only the position of the air needle needs to be adjusted). Charge intensity change threshold: 30% (when the charge intensity change is >30%, the original flow rate is no longer suitable, and the flow rate needs to be adjusted to increase or decrease to neutralize it). Distance threshold: 50μm (when the distance between the gas needle and the sample stage is ≥50μm, there is no risk of collision; when it is <50μm, adjustments are needed to avoid collision). Adjust the step size: raise the sample stage by 10μm and lower the gas needle by 10-20μm (make small adjustments to ensure the safe distance is stable and meets the standard).

[0053] Height Acquisition: After the sample stage is moved to the new observation area, the laser displacement sensor (measurement accuracy ±2nm) acquires the new height Z_new of the sample surface in real time and calculates the height change |Z_new-Z_old|; Pre-scan parameters: The pre-scan of the new area uses a beam current of 10pA and a time of 10 seconds, consistent with the pre-scan parameters, to ensure a unified standard for judging charge intensity; Flow rate adjustment logic: When the change in charge intensity is greater than 30%, if the new region has a stronger charge (increased bright spot ratio), increase the flow rate in steps of 0.05 sccm; if the charge is weaker, decrease the flow rate in steps of 0.05 sccm. Collision avoidance priority: First raise the Z-axis of the sample stage (to avoid the air needle from lowering too much and colliding with other components). If the sample stage has reached its maximum stroke (e.g., the maximum Z-axis stroke is 5mm), then lower the Z-axis of the air needle. If the air needle has been lowered to its lowest position (e.g., the lowest Z-axis position is 1mm) and the safe distance is still not met, stop moving the sample stage and prompt the user to adjust the sample placement height (e.g., increase the thickness of the sample base).

[0054] Second embodiment, see Figure 2As shown, a scanning electron microscope in-situ micro-region charge neutralization method according to an embodiment of this application includes the following steps: S100. Perform pressure testing on the airtightness of the gas system and interference intensity testing on the effectiveness of electromagnetic shielding; S200. Obtain the charge intensity information of the target sample through low beam current pre-scan imaging. Based on the temperature sensitivity identifier, three-dimensional morphology scanning results and experimental characterization requirements of the target sample, select the working gas type, determine the initial gas flow range and the initial position of the gas needle, pre-determine whether the safe distance between the initial position of the gas needle and the target sample meets the preset safety threshold, and at the same time verify the compatibility between the current vacuum degree and the initial gas flow rate to generate a personalized initial parameter scheme adapted to the characteristics of the target sample. S300. The working gas is introduced locally into the observation area of ​​the target sample to form a gas cloud that does not disrupt the vacuum environment of the scanning electron microscope sample chamber. The gas cloud is bombarded by the incident electron beam of the scanning electron microscope to ionize it and generate positive ions. The positive ions are deposited on the surface of the target sample and undergo a charge neutralization reaction with the excess electrons accumulated on the surface of the target sample. The surface charge density data of the target sample and the imaging quality parameters of the scanning electron microscope are collected in real time, and the gas flow rate, the XZ axis position of the gas needle and the electron beam current are dynamically adjusted. S400. Reset the gas needle to a safe position away from the sample stage and internal components of the sample chamber, verify the vacuum recovery status of the sample chamber, and at the same time verify the integrity of the vacuum curve, charge density curve, flow parameters and imaging images collected during the experiment.

[0055] Process connection logic: Only after the initial verification is passed can the parameter adjustment process begin; if the initial verification fails, the system will display a pop-up indicating the fault type (such as gas leakage or excessive electromagnetic interference), and the verification will be repeated after the fault is repaired. After the parameters are adjusted, the system automatically sends the initial parameters to the execution module, which then initiates gas injection and electron beam ionization. If an anomaly is detected during the neutralization process (such as a sudden drop in vacuum or a continuous exceedance of charge density), the corresponding logical steps will be followed. If the problem cannot be resolved, the experiment will be paused. After neutralization, first close the gas passage, keep the vacuum system running for 10 minutes to remove residual gas, and then perform reset and data verification. Experimental data storage: The system automatically exports experimental data (vacuum curve, charge density curve, flow parameters, imaging plots) in Excel and JPG formats, supporting subsequent data analysis and traceability; The method is applicable to a wide range of samples, including biological samples (cells, tissues, microorganisms), semiconductor materials (silicon wafers, flexible electronic materials), conventional insulating materials (polymers, ceramics), and weakly conductive materials (nanomaterials, metal oxides), covering most scanning electron microscope observation scenarios.

[0056] The charge effect on a sample is mainly due to the negative effect caused by the continuous accumulation of electrons on the sample surface after the interaction of incident electrons with the sample. There are two main approaches to addressing the charge effect: ① reducing charge accumulation on the sample surface; ② eliminating or suppressing electrons already accumulated on the sample surface. Since biological samples are primarily composed of insulating biomolecules such as proteins and nucleic acids, they are naturally non-conductive. Furthermore, the structure and composition of different biological samples vary significantly. Therefore, fundamentally solving the conductivity problem of all biological samples without altering their physical and chemical properties is extremely technically challenging. Thus, this project adopts the second design approach: actively eliminating the continuously accumulating charge on the sample surface to suppress the charge effect at its source.

[0057] This project utilizes a micro-area injection of high-purity nitrogen to create a localized nitrogen cloud within a very small area directly above the sample. Upon contact with the incident electron beam, this nitrogen cloud interacts and generates an ionization effect. The numerous positive ions (nitrogen ions) generated during ionization deposit on the sample surface, neutralizing the accumulated electrons. The resulting neutralized particles are completely electrically neutral and do not interfere with the incident or signal electrons, thus eliminating the sample's charge effect at its source while ensuring the overall high-vacuum environment of the electron microscope sample chamber remains intact.

[0058] Because the sample is not conductive, incident electrons cannot be conducted away in time after interacting with the sample, and continue to accumulate on the sample surface, thus generating a charging effect. This effect interferes with the electron beam focusing accuracy and signal detection stability, leading to negative problems such as abnormal contrast between light and dark areas, image drift, and edge distortion, which seriously affect image quality.

[0059] The system's accompanying ventilation device uses a micro-area precise injection method to locally introduce high-purity nitrogen gas onto the sample surface, forming a tiny gas cloud. When the nitrogen cloud is bombarded by the incident electron beam, it undergoes an ionization reaction and generates positively charged nitrogen ions. At the same time, this local gas cloud is extremely small, so it does not disrupt the overall high-vacuum environment of the sample chamber, ensuring the stability of the original imaging conditions of the electron microscope.

[0060] The nitrogen ions generated by ionization deposit on the sample surface, where they undergo a neutralization reaction with the excess electrons accumulated on the sample surface, ultimately forming uncharged nitrogen atoms. As the neutralization reaction continues, the excess electrons on the sample surface are completely eliminated, and the charging effect disappears, ensuring that the electron beam and signal electrons are not interfered with during subsequent imaging.

[0061] Unlike existing methods such as "metal coating" and "low-vacuum imaging," this project utilizes a "micro-area injection of high-purity nitrogen to ionize and neutralize charges" technique. This eliminates the charge effect in biological samples at its source without disrupting the high-vacuum environment of the electron microscope or altering the physicochemical properties of the samples. This avoids morphological artifacts and structural damage while ensuring high-resolution nanoscale imaging, addressing the core pain points of biological sample preparation, imaging, and analysis. To address the challenges of a large sample stage movement range and varying sample heights, the project achieves precise XZ-axis movement of the gas needle and coordinated mapping of the sample stage's XYZ-axis, ensuring the gas needle accurately follows the sample observation position. Furthermore, the dual-mode design of "initial position - working position" allows the device to be positioned away from the sample stage and internal components when not in operation, completely avoiding mechanical interference and collision risks. This allows for seamless integration without modifying the core structure of the electron microscope, preserving the original functionality of the equipment to the greatest extent possible. Taking into account the vacuum requirements of the electron microscope sample chamber and the differences in conductivity of different samples, a manual / automatic dual-mode flow control system is integrated at the front end of the gas passage. The gas flow rate can be precisely adjusted and real-time rate feedback can be achieved through mechanical valves or electronic signals. This not only meets the strict limitations on gas volume in high vacuum environments, but also flexibly adapts to the charge elimination requirements of different types of samples such as biological samples and weakly conductive materials, significantly expanding the range of applicable samples for electron microscopes.

[0062] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program goods. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program goods embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0063] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program goods according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0064] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0065] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0066] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A scanning electron microscope in-situ micro-area charge neutralization system, characterized in that, The method comprises the following steps: An initial verification module is configured to perform pressure testing on the sealing of the gas circuit system and interference strength detection on the effectiveness of electromagnetic shielding; An adjustment module is configured to obtain the charge intensity information of the target sample through low-beam pre-scanning imaging, select the type of working gas according to the temperature sensitivity identification, three-dimensional topography scanning results and experimental characterization requirements of the target sample, determine the initial gas flow range and the initial position of the gas needle, and pre-judge whether the safety distance between the initial position of the gas needle and the target sample meets the preset safety threshold, while verifying the adaptability of the current vacuum degree and the initial gas flow, to generate an individualized initial parameter scheme adapted to the characteristics of the target sample; An execution module is configured to introduce the working gas into the observation area of the target sample to form a gas cluster that does not destroy the vacuum environment of the scanning electron microscope sample chamber, use the incident electron beam of the scanning electron microscope to bombard the gas cluster to ionize it to generate positive ions, and the positive ions are deposited on the surface of the target sample and undergo charge neutralization reaction with the excess electrons accumulated on the surface of the target sample, real-time collection of the surface charge density data of the target sample and the scanning electron microscope imaging quality parameters, dynamic regulation of the gas flow, X-Z axis position of the gas needle and electron beam current; A reset verification module is configured to reset the gas needle to a safe position away from the sample stage and the internal components of the sample chamber, verify the recovery state of the vacuum degree of the sample chamber, and perform integrity verification on the vacuum degree curve, charge density curve, flow parameter and imaging graph collected during the experiment.

2. The in-situ micro-area charge neutralization system of a scanning electron microscope according to claim 1, characterized in that, When the initial verification module is configured to perform pressure testing on the sealing of the gas circuit system and interference strength detection on the effectiveness of electromagnetic shielding, it comprises the following steps: Apply air pressure to the gas circuit and keep it at a constant temperature for a predetermined time, and monitor the pressure decay in real time through a pressure sensor; When the pressure decay value is less than or equal to the preset pressure decay threshold, and the results of three consecutive pressure applications meet the decay requirement, it is determined that the gas circuit is sealed and qualified; Otherwise, it is determined that the gas circuit is not sealed and qualified.

3. The in-situ micro-area charge neutralization system of a scanning electron microscope according to claim 2, characterized in that, When the initial verification module is configured to perform pressure testing on the sealing of the gas circuit system and interference strength detection on the effectiveness of electromagnetic shielding, it further comprises the following steps: Detect the electromagnetic interference strength at the outlet end of the gas needle. When the electromagnetic interference strength is less than or equal to the preset interference threshold, it is determined that the shielding is qualified; When the electromagnetic interference strength is greater than the interference threshold, measure the connection resistance between the shielding layer and the electron microscope body ground terminal; When the electromagnetic interference strength is greater than the interference threshold, and the connection resistance is greater than the preset resistance threshold, regrind the ground terminal and tighten the connection; After regrinding the ground terminal and tightening the connection, if the connection resistance is less than or equal to the resistance threshold, detect the electromagnetic interference strength again; When the connection resistance is less than or equal to the resistance threshold, and the electromagnetic interference strength is greater than the interference threshold, adjust the gas needle away from the high-voltage components of the electron microscope; When the gas needle is adjusted to the limit position, and the electromagnetic interference strength is greater than the interference threshold, reduce the acceleration voltage.

4. The in-situ micro-area charge neutralization system of a scanning electron microscope according to claim 3, characterized in that, The adjustment module is configured to obtain the charging intensity information of the target sample by low-current pre-scanning imaging, select the working gas type according to the temperature sensitivity identification, three-dimensional topography scanning result and experimental characterization requirement of the target sample, determine the initial gas flow range and the initial position of the gas needle, pre-judge whether the safety distance between the initial position of the gas needle and the target sample meets the preset safety threshold, and simultaneously verify the adaptability of the current vacuum degree and the initial gas flow, and generate the individualized initial parameter scheme adapted to the characteristics of the target sample, comprising: acquiring the imaging graph of the target sample by electron beam pre-scanning, and acquiring the pixel ratio of the bright spot area in the imaging graph of the target sample; when the pixel ratio is less than or equal to a preset first pixel ratio threshold, it is a weak charging level; when the pixel ratio is greater than the first pixel ratio threshold and less than or equal to a preset second pixel ratio threshold, it is a medium charging level; when the pixel ratio is greater than the second pixel ratio threshold, it is a strong charging level, and the initial gas flow range and the initial gas needle distance are matched according to different charging levels; when the target sample is a semiconductor material, the coefficient of variation of backscattered electron signal intensity is calculated, and when the coefficient of variation of backscattered electron signal intensity is greater than a preset coefficient threshold, it is determined that the composition is uneven, and the gas flow is increased on the basis of the flow corresponding to the charging level; when the coefficient of variation of backscattered electron signal intensity is less than or equal to the coefficient threshold, it is determined that the composition is uniform, and the initial flow corresponding to the charging level is maintained.

5. A scanning electron microscope in-situ micro-area charge neutralization system according to claim 4, characterized in that, The adjustment module is configured to obtain the charging intensity information of the target sample by low-current pre-scanning imaging, select the working gas type according to the temperature sensitivity identification, three-dimensional topography scanning result and experimental characterization requirement of the target sample, determine the initial gas flow range and the initial position of the gas needle, pre-judge whether the safety distance between the initial position of the gas needle and the target sample meets the preset safety threshold, and simultaneously verify the adaptability of the current vacuum degree and the initial gas flow, and generate the individualized initial parameter scheme adapted to the characteristics of the target sample, comprising: when the target sample is a biological sample, the working gas type is nitrogen; when the target sample is a semiconductor sample, the working gas type is argon; when the target sample is not a biological sample and not a semiconductor sample, nitrogen is selected.

6. A scanning electron microscope in-situ micro-area charge neutralization system according to claim 5, characterized in that, The execution module is configured to locally introduce the working gas into the observation area of the target sample to form a gas cluster that does not destroy the vacuum environment of the scanning electron microscope sample chamber, use the incident electron beam of the scanning electron microscope to bombard the gas cluster to ionize it to generate positive ions, the positive ions are deposited on the surface of the target sample and undergo charge neutralization reaction with the excess electrons accumulated on the surface of the target sample, and real-time collection of the surface charge density data of the target sample and the imaging quality parameters of the scanning electron microscope, dynamic regulation of the gas flow, the X-Z axis position of the gas needle and the electron beam current, comprising: real-time acquisition of the vacuum degree of the sample chamber, calculation of the maximum allowable gas flow according to the preset equipment coefficient k of the scanning electron microscope model, and control of the gas flow during actual operation; When the vacuum degree is greater than or equal to a preset first vacuum degree threshold, the gas flow is reduced; When the vacuum degree is restored to be less than or equal to a preset second vacuum degree threshold after the gas flow is reduced, it is determined that the flow is out of limit, and the adjusted flow is maintained; When the vacuum degree is restored to be greater than the second vacuum degree threshold after the gas flow is reduced, the gas path sealing property is detected, when the gas path sealing is qualified, the vacuum system pumping speed is checked, when the pumping speed is lower than a preset percentage of the equipment standard value, the experiment is retried after the vacuum system is restarted, and if the pumping speed is normal and the vacuum still cannot be restored, the experiment is suspended.

7. A scanning electron microscope in-situ micro-area charge neutralization system according to claim 6, characterized in that, The execution module is configured to locally introduce the working gas into the target sample observation area to form a gas cluster that does not destroy the vacuum environment of a scanning electron microscope sample chamber, use a scanning electron microscope incident electron beam to bombard the gas cluster to ionize the gas cluster to generate positive ions, deposit the positive ions on the target sample surface, and cause charge neutralization reaction with the excess electrons accumulated on the target sample surface, and real-time collect the target sample surface charge density data and scanning electron microscope imaging quality parameters, and dynamically control the gas flow, the gas needle X-Z axis position and the electron beam current, and further include: Set a charge density threshold of the target sample surface, when the target sample surface charge density is reduced to be less than or equal to the charge density threshold within a preset time, the current parameters are maintained; When the target sample surface charge density is reduced to be greater than the charge density threshold within a preset time, whether the electron beam current is within a preset current threshold range is checked; When the current is less than the current threshold range, the electron beam current is increased; When the electron beam current is within the preset current threshold range, and the target sample surface charge density is greater than the charge density threshold, the distance from the center of the gas needle outlet end face to the surface of the sample observation area is reduced.

8. The in-situ micro-area charge neutralization system of a scanning electron microscope according to claim 7, characterized in that, The execution module is configured to locally introduce the working gas into the target sample observation area to form a gas cluster that does not destroy the vacuum environment of a scanning electron microscope sample chamber, use a scanning electron microscope incident electron beam to bombard the gas cluster to ionize the gas cluster to generate positive ions, deposit the positive ions on the target sample surface, and cause charge neutralization reaction with the excess electrons accumulated on the target sample surface, and real-time collect the target sample surface charge density data and scanning electron microscope imaging quality parameters, and dynamically control the gas flow, the gas needle X-Z axis position and the electron beam current, and further include: Calculate the bright spot area and the edge distortion rate; When the bright spot area is greater than a preset bright spot area threshold, and the edge distortion rate is less than or equal to a preset distortion rate threshold, the gas needle X-axis position is adjusted to be close to the bright spot center area until the bright spot area is less than or equal to the bright spot area threshold; If the fine adjustment times are greater than a preset number of times, and the bright spot area is greater than a preset bright spot area threshold, the gas flow is increased; When the edge distortion rate is greater than the distortion rate threshold, and the bright spot area is less than or equal to the bright spot area threshold, the gas flow is reduced until the distortion rate is less than or equal to the distortion rate threshold; When the edge distortion rate is greater than the distortion rate threshold after the gas flow is reduced, the beam current is reduced. When the bright spot area is greater than the preset bright spot area threshold and the edge distortion rate is greater than the distortion rate threshold, neutralization is immediately suspended, the gas passage is closed, and after the vacuum degree is restored to the second vacuum degree threshold, the initial parameters are reset at the weakly charged level and the neutralization process is restarted.

9. A scanning electron microscope in-situ micro-area charge neutralization system according to claim 8, characterized in that, The execution module is configured to locally introduce the working gas into the target sample observation area to form a gas cluster that does not destroy the vacuum environment of the scanning electron microscope sample chamber, use a scanning electron microscope incident electron beam to bombard the gas cluster to ionize the gas cluster to generate positive ions, deposit the positive ions on the target sample surface, and cause charge neutralization reaction with the excess electrons accumulated on the target sample surface, and in real time collect the target sample surface charge density data and scanning electron microscope imaging quality parameters, and dynamically control the gas flow, the X-Z axis position of the gas needle, and the electron beam current, and further comprise: After the sample stage moves to a new observation area, the new height of the sample surface is obtained by a laser displacement sensor, and the height change amount is obtained; When the height change amount is less than or equal to a preset change amount threshold, the gas needle Z-axis position is fine-tuned according to the height change amount, and the original gas flow is maintained; When the height change amount is greater than the change amount threshold, the maximum allowable flow is recalculated, when the new flow and the original flow have a deviation less than or equal to a preset deviation threshold, only the gas needle Z-axis position is adjusted; When the new flow and the original flow have a deviation greater than the deviation threshold, the gas flow is adjusted, and the new area is pre-scanned; When the charging intensity changes less than or equal to a preset change amount threshold after pre-scanning, the adjusted flow is maintained; Otherwise, the gas flow is adjusted; When the distance between the gas needle and the sample stage after moving is greater than or equal to a preset distance threshold, the position does not need to be adjusted; When the distance between the gas needle and the sample stage after moving is less than the distance threshold, the sample stage Z-axis is raised, and when the sample stage reaches the maximum stroke, the gas needle Z-axis is lowered until the distance between the gas needle and the sample stage is greater than or equal to the distance threshold.

10. A method of in-situ micro-area charge neutralization in a scanning electron microscope, characterized by, A scanning electron microscope in-situ micro-area charge neutralization system according to any one of claims 1 to 9, comprising the following steps: Pressure test the sealing performance of the gas path system, and detect the interference intensity of the electromagnetic shielding effectiveness; Obtain the charging intensity information of the target sample by low-current pre-scanning imaging, select the type of working gas according to the temperature sensitivity identification, three-dimensional topography scanning results and experimental characterization requirements of the target sample, determine the initial gas flow range and the initial position of the gas needle, pre-judge whether the safety distance between the initial position of the gas needle and the target sample meets the preset safety threshold, and verify the adaptability of the current vacuum degree and the initial gas flow, to generate a personalized initial parameter scheme suitable for the characteristics of the target sample; Locally introduce the working gas into the target sample observation area to form a gas cluster that does not destroy the vacuum environment of the scanning electron microscope sample chamber, use a scanning electron microscope incident electron beam to bombard the gas cluster to ionize the gas cluster to generate positive ions, deposit the positive ions on the target sample surface, and cause charge neutralization reaction with the excess electrons accumulated on the target sample surface, and in real time collect the target sample surface charge density data and scanning electron microscope imaging quality parameters, and dynamically control the gas flow, the X-Z axis position of the gas needle, and the electron beam current; The gas needle is reset to a safe position away from the sample stage and the sample chamber internal components, the sample chamber vacuum recovery state is checked, and the vacuum curve, charge density curve, flow parameter, and imaging graph collected during the experiment are checked for integrity.

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