Apparatus and method for adjusting position of electron probe

Abstract

This application discloses an apparatus and method for adjusting the position of an electron detector. The electron detector comprises a grid, a light guide component, and a photomultiplier tube component connected sequentially along a direction from near the objective lens to far from the objective lens. The apparatus includes a position adjustment mechanism connected to the electron detector for driving the electron detector to move relative to the objective lens along its own axis to change the position of the grid. A control unit is communicatively connected to a scanning electron microscope and the position adjustment mechanism. The control unit is configured to control the position adjustment mechanism to move the electron detector to a target position corresponding to the working distance between the scanning electron microscope and the sample tray. This application's solution, by setting up a position adjustment mechanism and a control unit, achieves precise control of the grid position, optimizes the electric field near the grid, and improves imaging quality.

Description

Technical Field

[0001] This application generally relates to the field of electronic detector technology. More specifically, this application relates to an apparatus and method for adjusting the position of an electronic detector. Background Technology

[0002] Scanning electron microscopy (SEM) is a key instrument for observing and analyzing the surface morphology of samples at the micro- and nano-scale. In SEM, secondary electron signals are the main source of contrast images of surface morphology, and the collection efficiency and quality of these signals directly determine the image sharpness, resolution, and signal-to-noise ratio.

[0003] Currently, commercial scanning electron microscopes commonly use the Everhart-Thornley (ET) electron detector as their standard secondary electron detector. A typical ET detector mainly consists of a grid, a scintillator, a light guide assembly, and a photomultiplier tube assembly. Its working principle is as follows: an appropriate bias voltage (e.g., +200V) is applied to the grid to create a collecting electric field, attracting low-energy secondary electrons emitted from the sample surface; the collected electrons are accelerated and then strike the scintillator, which is subjected to a high voltage (e.g., +10kV), generating a light signal; this light signal is transmitted through the light guide assembly to the photomultiplier tube assembly, and finally converted into an electrical signal for imaging.

[0004] In practical applications, the position of the ET detector is usually fixed, and the relative position and angle of its front-end grid with respect to the objective lens and the sample are not adjustable; that is, the grid is rigidly mounted on the side wall of the sample chamber. This fixed mounting method leads to a long-standing and unresolved technical problem: when the working distance changes, the spatial configuration between the grid, the lower objective lens pole piece, and the sample surface changes significantly, causing a passive change in the electric field distribution near the grid, making it impossible to maintain the optimal collection state for secondary electrons.

[0005] In view of this, there is an urgent need to provide a device and method for adjusting the position of an electronic detector, which can enable the detector's position to be actively and accurately adjusted as the working distance changes, thereby achieving stable and high-quality imaging. Summary of the Invention

[0006] In order to at least solve one or more of the technical problems mentioned above, this application proposes an apparatus and method for adjusting the position of an electronic detector to achieve stable imaging in several aspects.

[0007] In a first aspect, this application provides an apparatus for adjusting the position of an electron detector, wherein the electron detector comprises a grid, a light guide component, and a photomultiplier tube component connected in sequence along a direction from near the objective lens to far from the objective lens; the apparatus includes: a position adjustment mechanism connected to the electron detector for driving the electron detector to move relative to the objective lens along its own axis to change the position of the grid; and a control unit communicatively connected to a scanning electron microscope and the position adjustment mechanism; the control unit is configured to control the position adjustment mechanism to drive the electron detector to move to a target position corresponding to the working distance between the scanning electron microscope and the sample tray.

[0008] In some embodiments, the position adjustment mechanism includes: a slide groove mounted on the light guide component; a support assembly, one end of which is slidably engaged with the slide groove and the other end of which is fixed to the inner wall of the scanning electron microscope chamber; and a driver disposed outside the chamber, the driving end of which is connected to the photomultiplier tube component.

[0009] In some embodiments, the support assembly includes a support rod fixed to the inner wall of the cavity and a roller disposed at the front end of the support rod and rollingly engaging with the groove.

[0010] In some embodiments, the actuator includes two hydraulic telescopic rods, which are respectively arranged above and below the photomultiplier tube component.

[0011] In some embodiments, the two ends of each hydraulic telescopic rod are respectively hinged to the mounting portion on the outer wall of the cavity and the mounting portion on the photomultiplier tube component via pins.

[0012] In some embodiments, a vacuum bellows is further included, with a first end of the vacuum bellows sealed to an opening on the side wall of the chamber and a second end sealed to the outer periphery of the photomultiplier tube component, so that the photomultiplier tube component can maintain the vacuum seal of the chamber when it moves relative to the chamber.

[0013] In some embodiments, the control unit includes: a storage module for storing the correspondence between the working distance and the target position of the electronic detector; and a signal processing module for receiving the signal of the working distance and generating a drive signal according to the correspondence and sending it to the position adjustment mechanism.

[0014] In some embodiments, the correspondence is configured as follows: in response to a change in the working distance, the electronic detector is controlled to move along its axis to a suitable target position; when the working distance is within the first preset range, the electronic detector is controlled to move along its axis away from the objective lens; when the working distance is within the second preset range, the electronic detector is controlled to move along its axis towards the objective lens.

[0015] In a second aspect, this application provides a method for controlling the position of an electronic detector, applied to the aforementioned apparatus for adjusting the position of an electronic detector. The method includes: acquiring a set working distance of a scanning electron microscope; determining a target position corresponding to the set working distance based on a pre-stored mapping relationship between the working distance and the target position of the electronic detector; generating a control signal based on the target position and driving the position adjustment mechanism to move the electronic detector to the target position.

[0016] In some embodiments, determining the target location based on a pre-stored mapping relationship is performed by querying a mapping relationship table pre-stored in the control unit.

[0017] By using the electron detector position adjustment device provided above, this embodiment of the application achieves precise control of the grid position through the setting of a position adjustment mechanism, breaking the positional limitations caused by the fixed installation of traditional electron detectors and creating structural conditions for optimizing the electric field distribution near the grid. Furthermore, the device in this application, by setting a control unit, achieves intelligent adaptation between the electron detector position and the working distance, enabling the electric field distribution near the grid to actively adjust to the optimal state as the working distance changes, maximizing the secondary electron collection efficiency at different working distances, and thus significantly improving the quality of sample morphology images generated by scanning electron microscopy. Attached Figure Description

[0018] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, and the same or corresponding reference numerals denote the same or corresponding parts, wherein:

[0019] Figure 1 A schematic diagram of the structure of the device for adjusting the position of the electronic detector according to an embodiment of this application is shown; Figure 2 This paper shows a cross-sectional schematic diagram of the electric field distribution near the grid during a simulation experiment according to an embodiment of this application. Figure 3 The diagram shows the position and symbol of the ET electronic detector during the simulation experiment of an embodiment of this application; Figure 4 The diagram shows the secondary electron collection efficiency data at different locations obtained from simulation experiments of embodiments of this application.

[0020] In the diagram: 100, electronic detector; 200, device for adjusting the position of the electronic detector; 300, outer casing; 101. Grid; 102. Light guide component; 103. Photomultiplier tube component; 201. Slide groove; 202. Roller; 203. Support rod; 204. Hydraulic telescopic rod; 205. Vacuum bellows; 206. Pin; 301. Objective lens; 302. Sample tray; 303. Sample. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] It should be understood that the terms "comprising" and "including" used in the specification and claims of this application indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0023] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this specification and claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0024] As used in this specification and claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0025] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0026] like Figure 1 As shown, in some embodiments, this application provides an apparatus 200 for adjusting the position of an electron detector, wherein the electron detector 100 includes a grid 101, a light guide component 102, and a photomultiplier tube component 103 connected in sequence along a direction from near the objective lens 301 to away from the objective lens 301; the apparatus includes: a position adjustment mechanism connected to the electron detector 100 for driving the electron detector 100 to move relative to the objective lens 301 along its own axis to change the position of the grid 101; and a control unit communicatively connected to a scanning electron microscope and the position adjustment mechanism; the control unit is configured to control the position adjustment mechanism to drive the electron detector 100 to move to a target position corresponding to the working distance, based on the working distance between the scanning electron microscope and the sample tray 302.

[0027] In the scheme of this application, the electron detector 100 is specifically an ET (Everhart-Sornley) electron detector 100. As the core detection component of the scanning electron microscope, it is connected in sequence with a grid 101, a light guide component 102 and a photomultiplier tube component 103 along the direction from near the objective lens 301 to away from the objective lens 301. The three components work together to form a complete electronic signal collection and conversion link, providing basic support for subsequent image generation.

[0028] The device for adjusting the spatial position of the electron detector 100 (hereinafter referred to as the device) mainly consists of a position adjustment mechanism and a control unit. Specifically, the position adjustment mechanism is directly connected to the electron detector 100, and its core function is to drive the electron detector 100 to move smoothly relative to the objective lens 301 along its own axis. By changing the overall spatial position of the electron detector 100, the precise control of the position of the grid 101 is indirectly achieved. The dynamic adjustment of the position of the grid 101 can optimize the non-uniform electric field distribution in its vicinity, thereby creating favorable conditions for secondary electron collection at different working distances.

[0029] The control unit establishes communication connections with both the scanning electron microscope and the position adjustment mechanism. It possesses key functions such as data reception, analysis, processing, and command transmission, providing core support for the precise control of the electron detector 100's position. Notably, to ensure the targeted nature and effectiveness of the control, the control unit pre-stores specific matching data. This data corresponds to the target position data of the electron detector 100 at different working distances between the scanning electron microscope (specifically, the pole piece under the scanning electron microscope objective) and the sample tray 302. This matching data is not randomly set; it is pre-calibrated based on the core requirements of optimizing the electric field distribution near the grid 101 and maximizing secondary electron collection efficiency. This provides a reliable data foundation for the subsequent rapid and precise adjustment of the electron detector 100's position according to the actual working distance.

[0030] During operation, the control unit acquires the actual working distance information of the scanning electron microscope or the user inputs a target working value in the software. After comparing the target position that matches the current working distance with the preset matching data, it sends a precise control command to the position adjustment mechanism to drive the electron detector 100 to move to the target position. This ensures that the electric field distribution near the grid 101 always maintains the best matching state with the current working distance, and ensures that the secondary electron collection efficiency is stable at the optimal level.

[0031] The device in this application achieves precise control of the position of the grid 101 by setting a position adjustment mechanism, breaking the positional limitations caused by the fixed installation of the traditional electron detector 100, and creating structural conditions for optimizing the electric field distribution near the grid 101. In addition, the device in this application achieves intelligent adaptation between the position of the electron detector 100 and the working distance by setting a control unit, so that the electric field distribution near the grid 101 can be actively adjusted to the optimal state as the working distance changes, maximizing the secondary electron collection efficiency at different working distances, and thus significantly improving the quality of the morphology image of sample 303 generated by scanning electron microscopy.

[0032] In one specific embodiment, the position adjustment mechanism includes: a slide 201 mounted on the light guide component 102; a support assembly, one end of which slides in engagement with the slide 201 and the other end of which is fixed to the inner wall of the scanning electron microscope chamber; and an actuator disposed outside the chamber, the drive end of which is connected to the photomultiplier tube component 103. The support assembly includes a support rod 203 fixed to the inner wall of the chamber and a roller 202 disposed at the front end of the support rod 203 and rollingly engaging with the slide 201. The actuator includes two hydraulic telescopic rods 204, which are respectively arranged above and below the photomultiplier tube component 103.

[0033] In this application, the position adjustment mechanism is the core execution structure for achieving precise spatial position adjustment of the electronic detector 100. Specifically, it includes a slide 201, a support assembly, and a driver. Specifically, the slide 201 is fixedly installed on the light guide component 102 of the electronic detector 100, providing a directional guide path for the detector's movement. The support assembly includes two sets of support rods 203 and rollers 202 disposed within the cavity enclosed by the housing 300. One end of the support rod 203 is fixedly connected to the inner wall of the scanning electron microscope cavity, and this end has a fixed position, length, and angle that do not change. The other end is equipped with a roller 202. The roller 202 and the slide 201 form a suitable sliding fit structure, allowing the electronic detector 100 to move smoothly back and forth along its own axis by means of the roller 202 rolling within the slide 201, effectively limiting the detector's movement trajectory and preventing deviation.

[0034] The actuator employs a hydraulic telescopic rod 204 structure, specifically positioned outside the scanning electron microscope chamber. This avoids interference with the vacuum environment within the chamber and facilitates subsequent installation, debugging, and maintenance. To ensure the stability of the driving force transmission and the accuracy of the detection position adjustment, two hydraulic telescopic rods 204 are configured, symmetrically installed above and below the corresponding electron detector 100 outside the chamber, forming a balanced dual-drive support structure. The base of the hydraulic telescopic rod 204 is fixedly connected to the external sidewall of the chamber via a pin 206 that can rotate around its central axis. Its drive end is also connected to the photomultiplier tube component 103 of the electron detector 100 via a pin 206 that can rotate around its central axis. This rotatable, flexible connection method can flexibly adapt to the angle fine-tuning during the movement of the electron detector 100, effectively avoiding problems such as jamming or stress concentration during driving force transmission, ensuring the smoothness and effectiveness of power transmission.

[0035] During operation, the hydraulic telescopic rod 204 generates a precise and controllable driving force through its telescopic movement. Combined with the directional guidance of the support components and the slide 201, it can stably and accurately drive the entire electronic detector 100 to move along its own axis, thereby realizing the dynamic adjustment of the position of the grid 101 and providing reliable power support for adapting to different working distances and optimizing the electric field distribution.

[0036] In one specific implementation, the two ends of each hydraulic telescopic rod 204 are respectively hinged to the mounting part on the outer wall of the cavity and the mounting part on the photomultiplier tube component 103 via pins.

[0037] In the scheme of this application, mounting parts are provided on the outer wall of the chamber and the photomultiplier tube component 103. One end of each hydraulic telescopic rod 204 is hinged to the mounting part pre-set on the outer wall of the scanning electron microscope chamber via a pin, and the other end is hinged to the corresponding mounting part designed on the photomultiplier tube component 103 of the electron detector 100 via a pin.

[0038] In one specific implementation, a vacuum bellows 205 is also included. The first end of the vacuum bellows 205 is sealed and fixed to an opening on the side wall of the chamber, and the second end is sealed and fixed to the outer periphery of the photomultiplier tube component 103, so that the photomultiplier tube component 103 can maintain the vacuum seal of the chamber when it moves relative to the chamber.

[0039] In the scheme of this application, the device also includes a vacuum bellows 205, the first end of which is sealed and fixed to a pre-set opening on the side wall of the scanning electron microscope chamber, and the second end is sealed and connected to the corresponding position on the outer periphery of the photomultiplier tube component 103 of the electron detector 100. Both connections strictly ensure the reliability of the seal and prevent vacuum leakage.

[0040] Those skilled in the art will understand that the vacuum bellows 205 possesses excellent flexibility and angular adaptability. It can flexibly contract or expand as the photomultiplier tube component 103 moves, and it can also adapt to small angular changes during detector movement, without hindering the movement of the electron detector 100 along its own axis. This ensures that the photomultiplier tube component 103 can be smoothly adjusted relative to the chamber. Simultaneously, its reliable sealing structure maintains a constant vacuum within the chamber. A vacuum environment is essential for the normal operation of a scanning electron microscope, ensuring the stability of electron signal transmission and detection accuracy. Therefore, based on the dynamic adjustment of the detector position, it provides a stable environment for the efficient collection of secondary electrons and subsequent image quality improvement.

[0041] In one specific implementation, the control unit includes: a storage module for storing the correspondence between the working distance and the target position of the electronic detector 100; and a signal processing module for receiving the working distance signal and generating a drive signal according to the correspondence to send to the position adjustment mechanism.

[0042] In the solution of this application, the control unit integrates a storage module and a signal processing module. The core function of the storage module is to pre-store the correspondence data between different working distances between the scanning electron microscope and the sample tray 302 and the target position of the electron detector 100. This correspondence is not randomly set, but is based on the core requirements of optimal electric field distribution near the grid 101 and maximizing secondary electron collection efficiency. It is pre-calibrated through preliminary simulation analysis and actual testing, providing reliable data support for subsequent rapid and accurate position matching.

[0043] The signal processing module is responsible for signal reception, analysis, and command generation. During operation, it receives the actual working distance signal from the scanning electron microscope in real time, then quickly retrieves the corresponding data stored in the storage module, analyzes and calculates to determine the target position of the electron detector 100 that is compatible with the current working distance, and generates a corresponding precise drive signal. This signal is sent to the position adjustment mechanism, which then drives the position adjustment mechanism to move the electron detector 100 to the target position. Ultimately, this achieves dynamic adaptation between the working distance and the detector position, ensuring that the secondary electron collection efficiency is always at the optimal level.

[0044] In one specific implementation, the correspondence is configured as follows: in response to a change in working distance, the electronic detector 100 is controlled to move along its axis to a suitable target position; when the working distance is within the first preset range, the electronic detector is controlled to move along its axis away from the objective lens; when the working distance is within the second preset range, the electronic detector is controlled to move along its axis towards the objective lens.

[0045] In this application, the direction of movement of the electronic detector is determined based on whether the working distance value falls within a first preset interval or a second preset interval, thereby determining the target position. Specifically, when the working distance is within the first preset interval, the electronic detector is controlled to move along its axis away from the objective lens to determine the appropriate target position; when the working distance is within the second preset interval, the electronic detector is controlled to move along its axis towards the objective lens to determine the appropriate target position. Specifically, when the working distance is within the first preset interval, the target position is a first displacement that moves the electronic detector 100 along its axis away from the objective lens 301; when the working distance is within the second preset interval, the target position is a second displacement that moves the electronic detector 100 along its axis towards the objective lens 301.

[0046] More specifically, when the working distance is within the first preset range of 5mm to 8mm, the target position is a first displacement of 3mm that moves the electronic detector 100 away from the objective lens 301 along its axis; when the working distance is within the second preset range of 8mm to 20mm, the target position is a second displacement of 9mm that moves the electronic detector 100 closer to the objective lens 301 along its axis.

[0047] It is worth noting that the correspondence between the first preset interval and the first displacement, and the correspondence between the second preset interval and the second displacement in this scheme, are not subjectively set, but are precisely calibrated based on targeted simulation experimental analysis and actual test verification, and have sufficient scientific basis. The underlying logic of this simulation experiment is to establish a three-dimensional electric field simulation model including the objective lens pole piece, the grid, and the sample surface to simulate the electric field distribution near the grid when it is at different positions along the detector axis at different working distances. Based on this electric field distribution, the trajectory of secondary electrons emitted from the sample surface is further tracked, the number of electrons arriving at the scintillator is counted, and the secondary electron collection efficiency at each position is calculated. By systematically changing the working distance and the grid position, the optimal grid position dataset that maximizes the collection efficiency is obtained. Finally, based on the summary results of this simulation dataset, those skilled in the art can determine that there is a clear correspondence between the working distance and the optimal grid displacement. On this basis, a segmented mapping rule can be established, and the correspondence stored in the control unit can be formed accordingly.

[0048] Specifically, the correspondence can be reflected as the following piecewise function or position setting: when the working distance is in the range of 5 mm to 8 mm, the control unit outputs a command to move the grid along the detector axis toward the objective lens by 3 mm (i.e., displacement Δx = -3 mm); when the working distance is in the range of 8 mm to 20 mm, the control unit outputs a command to move the grid along the detector axis toward the objective lens by 9 mm (i.e., displacement Δx = +9 mm).

[0049] Those skilled in the art will understand that the aforementioned displacements of -3 mm and +9 mm are determined based on the inflection point (at the 8 mm position) where the secondary electron collection efficiency undergoes a significant change, as observed in the simulation experiment. While ensuring the achievement of the beneficial effects described in this invention, those skilled in the art can appropriately adjust or further subdivide the displacement ranges according to the actual system configuration, simulation accuracy, or optimization objectives. Such variations based on the same inventive concept should all fall within the protection scope of this invention.

[0050] like Figures 2-4 As shown, this scheme aims to determine the optimal position of the ET electron detector 100 at different working distances. A specific simulation of the effect of the spatial position of the ET electron detector 100 on the secondary electron absorption efficiency is conducted, with simulation conditions strictly conforming to the actual detection scenario. Specifically, the number of secondary electrons emitted from the surface of sample 303 is set to 5000. A +200V bias voltage is applied to the grid 101, and a +10kV high voltage is applied to the scintillator. The axis of the ET electron detector 100 component maintains a 15° angle with the horizontal plane. The secondary electron collection effect at different positions is simulated by moving the detector back and forth along the axis (the receiving efficiency is calculated as the number of secondary electrons received by the scintillator surface / the number of secondary electrons emitted by the sample surface × 100%).

[0051] like Figure 4 As shown, various detector positions were set in the simulation experiment. The green inverted triangle represents the original position, the black square, red circle, and blue upper triangle represent positions along the axis that are 9mm, 6mm, and 3mm away from the lower pole piece of objective lens 301, respectively, and the purple rhomboid square, gold left triangle, and cyan right triangle represent positions along the axis that are 3mm, 6mm, and 9mm closer to the lower pole piece of objective lens 301, respectively.

[0052] Simulation results show that the electric field distribution near the grid 101 changes with the working distance. Maximizing secondary electron collection efficiency is achieved when the position of the electron detector 100 dynamically adapts to the working distance. Specifically, when the working distance is 5mm~8mm, the highest collection efficiency is achieved at the position 3mm away from the lower pole piece of the objective lens 301 along the axis (i.e., the blue upper triangle line is at the top). When the working distance is 8mm~20mm, the highest collection efficiency is achieved at the position 9mm closer to the lower pole piece of the objective lens 301 along the axis (i.e., the cyan right triangle line is at the top). Based on this simulation conclusion, and considering the typical working distance range of 5mm~20mm in practical applications, a precise correspondence is determined: when the working distance between the scanning electron microscope and the sample tray 302 is 5mm to 8mm, the target position of the electron detector 100 is the position moved 3mm away from the objective lens 301 along its own axis. At this point, the electric field distribution near the grid 101 can attract secondary electrons to the greatest extent. When the working distance is 8mm to 20mm, the target position is the position that is moved 9mm from the initial position along its own axis towards the objective lens 301. This position ensures that the electric field distribution is always in the optimal state of secondary electron collection, thereby ensuring that the quality of the morphology image of sample 303 generated by scanning electron microscope at different working distances is steadily improved. By optimizing the secondary electron collection efficiency, the image signal-to-noise ratio is effectively improved.

[0053] In some embodiments, this application provides a method for controlling the position of an electron detector, applied to the aforementioned apparatus 200 for adjusting the position of the electron detector. The method includes: acquiring a set working distance of a scanning electron microscope; determining a target position corresponding to the set working distance based on a pre-stored mapping relationship between the working distance and the target position of the electron detector 100; generating a control signal based on the target position and driving a position adjustment mechanism to move the electron detector 100 to the target position. Determining the target position based on the pre-stored mapping relationship is performed by querying a mapping relationship table pre-stored in the control unit.

[0054] In this application, a method for controlling the position of an electron detector is provided. This method is specifically applied to the aforementioned device 200 with adjustable electron detector position. Its core purpose is to achieve dynamic adaptation between the position of the electron detector 100 and the working distance of the scanning electron microscope through automated and precise control logic, thereby ensuring the optimal efficiency of secondary electron collection.

[0055] The specific execution flow of the control method is as follows: First, the signal processing module of the control unit receives the set working distance from the scanning electron microscope in real time. The set working distance can be measured in real time by a high-precision displacement sensor (such as an encoder or laser interferometer) integrated in the drive system of the sample 303, or it can be a target working value input by the user in the software.

[0056] Next, the corresponding target position is determined according to the pre-stored mapping relationship between the working distance and the target position of the electronic detector 100. This mapping relationship is a mapping relationship table pre-calibrated based on the conclusions of previous special simulation experiments, and this table is stored in the storage module of the control unit. Therefore, the process of determining the target position is executed accurately by querying the pre-stored mapping relationship table through the signal processing module to ensure the adaptability of the target position to the current working distance.

[0057] Finally, the signal processing module generates a corresponding precise control signal based on the queried target position and sends the signal to the position adjustment mechanism. This drives the hydraulic telescopic rod 204, support components, and slide 201 in the position adjustment mechanism to work together, causing the electron detector 100 to move smoothly along its own axis to the target position. This ensures that the electric field distribution near the grid 101 is always optimally matched with the current working distance, ultimately maximizing the secondary electron collection efficiency at different working distances and ensuring a stable improvement in the quality of the morphology image of the sample 303 generated by the scanning electron microscope.

[0058] The solution proposed in this application determines the corresponding target position by using a pre-stored mapping relationship between the working distance and the target position of the electron detector 100. This allows for rapid and accurate matching of the optimal target position to the current working distance, avoiding the blindness of position adjustment and ensuring the targeted and scientific nature of the electric field distribution optimization near the grid 101. Furthermore, the solution achieves automated and precise adjustment of the electron detector 100's position by generating a control signal based on the target position and driving the position adjustment mechanism. Position adaptation can be completed without manual intervention, improving operational convenience and control efficiency. It also ensures that the electron detector 100 moves stably to the target position, keeping the electric field distribution near the grid 101 in an optimal state for secondary electron collection, ultimately maximizing secondary electron collection efficiency and significantly improving the quality of the morphology images of sample 303 generated by scanning electron microscopy at different working distances.

[0059] While numerous embodiments of this application have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will arise for those skilled in the art without departing from the spirit and intent of this application. It should be understood that various alternatives to the embodiments of this application described herein may be employed in the practice of this application. The appended claims are intended to define the scope of protection of this application and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A device (200) for adjusting the position of an electron detector, wherein the electron detector (100) comprises, along a direction from near the objective lens (301) to away from the objective lens (301), a grid (101), a light guide component (102), and a photomultiplier tube component (103) connected in sequence; characterized in that, The device includes: A position adjustment mechanism, connected to the electronic detector (100), is used to drive the electronic detector (100) to move relative to the objective lens (301) along its own axis to change the position of the grid (101); and A control unit is communicatively connected to the scanning electron microscope and the position adjustment mechanism; the control unit is configured to control the position adjustment mechanism to drive the electron detector (100) to move to a target position corresponding to the working distance, based on the working distance between the scanning electron microscope and the sample tray (302).

2. The apparatus according to claim 1, characterized in that, The position adjustment mechanism includes: A chute (201) is mounted on the light guide component (102); The support assembly has one end slidably engaged with the groove (201) and the other end fixed to the inner wall of the chamber of the scanning electron microscope; A driver is located outside the cavity, and the driving end of the driver is connected to the photomultiplier tube component (103).

3. The apparatus according to claim 2, characterized in that, The support assembly includes a support rod (203) fixed to the inner wall of the cavity and a roller (202) disposed at the front end of the support rod (203) and rollingly engaged with the slide groove (201).

4. The apparatus according to claim 2, characterized in that, The actuator includes two hydraulic telescopic rods (204), which are respectively arranged above and below the photomultiplier tube component (103).

5. The apparatus according to claim 4, characterized in that, Both ends of each of the hydraulic telescopic rods (204) are respectively hinged to the mounting part on the outer wall of the cavity and the mounting part on the photomultiplier tube component (103) by pins.

6. The apparatus according to any one of claims 2 to 5, characterized in that, It also includes a vacuum bellows (205), the first end of which is sealed and fixed to an opening on the side wall of the chamber, and the second end is sealed and fixed to the outer periphery of the photomultiplier tube component (103), so that the photomultiplier tube component (103) can maintain the vacuum seal of the chamber when it moves relative to the chamber.

7. The apparatus according to claim 1, characterized in that, The control unit includes: A storage module is used to store the correspondence between the working distance and the target position of the electronic detector (100); The signal processing module is used to receive the signal of the working distance and generate a drive signal according to the correspondence and send it to the position adjustment mechanism.

8. The apparatus according to claim 7, characterized in that, The correspondence is configured such that, in response to a change in the working distance, the electronic detector (100) is controlled to move along its axis to a suitable target position; When the working distance is within the first preset range, the electronic detector (100) is controlled to move along its axis in a direction away from the objective lens (301); When the working distance is within the second preset range, the electronic detector (100) is controlled to move along its axis toward the objective lens (301).

9. A method for controlling the position of an electronic detector, characterized in that, An apparatus for adjusting the position of an electronic detector according to any one of claims 1 to 8, the method comprising: Obtain the set working distance of the scanning electron microscope; Based on the pre-stored mapping relationship between working distance and target position of electronic detector, determine the target position corresponding to the set working distance; A control signal is generated based on the target position, and the position adjustment mechanism is driven to move the electronic detector to the target position.

10. The method according to claim 9, characterized in that, The determination of the target location based on the pre-stored mapping relationship is performed by querying the mapping relationship table pre-stored in the control unit.

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