A method of installing a confocal imaging assisted secondary ion extraction system

Abstract

The application provides a kind of confocal imaging assisted secondary ion extraction system installation method, belong to secondary ion mass spectrum field.The method provided by the application comprises: the ion beam emitted by primary ion optical system is bombarded to sample, imaging system obtains beam spot imaging image, and the position of sample stage is automatically adjusted according to imaging image to make the center of ion beam spot coincide with the center of sample;Determine the first distance from sample stage to extraction flat plate and the second distance from extraction cavity to extraction flat plate;According to the spherical mirror parameters of reflecting sphere mirror, the third distance of secondary ion extraction system imaging focus reaching sample stage is calculated;According to the difference between third distance and first distance, second distance, the relative distance between extraction cavity and extraction flat plate is calculated;According to relative distance, installation extraction cavity.The installation method of confocal imaging assisted secondary ion extraction system provided by the application can solve the problems of low secondary ion extraction efficiency and poor analysis accuracy.

Description

Technical Field

[0001] This application relates to the field of secondary ion mass spectrometry technology, and in particular to an installation method for a confocal imaging-assisted secondary ion extraction system. Background Technology

[0002] In the field of ion mass spectrometry, secondary ion extraction systems are core equipment for achieving high-precision analysis of sample components. They collect secondary ions generated by ion beam bombardment of the sample surface and combine this with mass spectrometry analysis to obtain information on the elemental composition and distribution of the sample. These systems are widely used in materials science, life sciences, semiconductor testing, and other fields. The efficiency of secondary ion extraction is directly related to the spatial coordination accuracy of the system's components; therefore, precise control of the positional association between the imaging system and the extraction system, as well as the matching relationship between the ion beam path and the extraction components, is necessary during installation.

[0003] Currently, the installation methods for existing secondary ion extraction systems typically involve two core steps: imaging and positioning, and component assembly. The imaging system uses optical elements to capture images of the beam spot formed by the ion beam bombarding the sample, assisting in adjusting the sample stage position to align the beam spot with the sample center. The extraction system constructs a secondary ion transport path by installing components such as extraction plates and extraction chambers. The extraction plates are used to screen secondary ions in the beam spot region, and the extraction chambers are used to constrain ion transport and reduce losses. However, existing installation procedures largely rely on empirical operation or simple mechanical positioning, lacking systematic benchmark calibration and parameter calculation logic.

[0004] The existing technology has the following key problems: First, the spatial reference of the imaging system and the extraction system is not effectively unified. The optical center and the mechanical center often have horizontal plane offset or axis misalignment, resulting in visual deviation in beam spot imaging. The alignment accuracy between the beam spot center and the sample center is insufficient, affecting the accuracy of the target area for subsequent ion extraction. Second, the calculation of distance parameters of the extraction components (such as the distance from the sample to the extraction plate and the distance from the extraction plate to the extraction cavity) lacks scientific basis and does not take into account core parameters such as the optical characteristics of the reflecting spherical mirror and the beam propagation law. Inappropriate distance can easily lead to secondary ion transmission blockage or diffusion loss, reducing extraction efficiency. Third, the installation of imaging components (such as CCD and spectrophotometer) and light sources and extraction components lacks standardized calibration procedures. Problems such as optical path eccentricity and uneven illumination occur frequently, further aggravating beam spot positioning errors and ion transmission losses, making it difficult to meet the needs of high-precision analysis scenarios. Summary of the Invention

[0005] In view of this, this application provides an installation method for a confocal imaging-assisted secondary ion extraction system to solve the problems of low secondary ion extraction efficiency and poor analytical accuracy.

[0006] Specifically, this application is implemented through the following technical solution:

[0007] This application provides a method for installing a confocal imaging-assisted secondary ion extraction system. The secondary ion extraction system includes an imaging system and an extraction system. The extraction system includes an extraction cavity, a reflecting spherical mirror, and an extraction plate. The extraction cavity is located in the direction of the ion beam exiting the sample. The reflecting spherical mirror is located on both sides of the extraction cavity. The extraction plate is positioned on the path of the exiting beam before it enters the extraction cavity and has an opening corresponding to the beam. The installation method includes:

[0008] An ion beam emitted by an ion optics system bombards a sample, and the imaging system acquires a beam spot image. Based on the image, the sample stage position is automatically adjusted so that the center of the ion beam spot coincides with the center of the sample.

[0009] Determine a first distance from the sample stage to the extraction plate and a second distance from the extraction chamber to the extraction plate;

[0010] The third distance from the imaging focal point of the secondary ion extraction system to the extraction plate is calculated based on the spherical mirror parameters of the reflecting spherical mirror.

[0011] The relative distance between the extraction chamber and the sample stage is calculated based on the difference between the third distance and the first and second distances.

[0012] The extraction cavity is installed according to the relative distance.

[0013] A second aspect of this application provides a confocal imaging-assisted secondary ion extraction system, the secondary ion extraction system comprising:

[0014] An imaging system is used to acquire beam spot imaging images of ion beam bombardment of samples and to assist in locating the position of the beam spot center relative to the sample center.

[0015] The extraction system includes an extraction cavity, a reflecting spherical mirror, an extraction plate, a primary ion optical system, and a sample stage;

[0016] The extraction cavity is located in the direction of the ion beam that bombards the sample. The extraction cavity has an opening near the sample side. The extraction cavity is installed with the extraction plate by a relative distance calculated based on the difference between the third distance and the first and second distances.

[0017] The reflecting spherical mirrors are located on both sides of the extraction cavity to cooperate with the imaging system to determine the position of the imaging focal point and to provide spherical mirror parameter support for calculating the third distance from the imaging focal point to the sample stage.

[0018] The extraction plate is positioned on the motion path of the emitted beam spot before it enters the extraction cavity. It has an opening corresponding to the beam spot and is used to determine the first distance in conjunction with the sample stage and the second distance in conjunction with the extraction cavity, providing a positional and geometric parameter reference for the calculation of the relative distance.

[0019] The primary ion optical system is used to emit an ion beam to bombard the sample, the sample stage is used to adjust the sample position so that the beam spot center coincides with the sample center, and the position parameters of the sample stage are used to calculate the first distance from the sample stage to the extraction plate.

[0020] The installation method of the confocal imaging-assisted secondary ion extraction system provided in this application, compared with the poor extraction accuracy and effect of installation based on experience, automatically and quantitatively calculates the installation position of each module according to the size information of the device in the extraction system, ensuring that the beam spot is precisely aligned with the sample center, and at the same time, the extraction chamber can extract the secondary sputtered ions to the maximum extent, ensuring the optimal extraction effect. First, the imaging system acquires beam spot images and automatically adjusts the sample stage position to ensure the beam spot center coincides with the sample center. This ensures precise matching between the ion beam bombardment area and the sample analysis area, reducing analytical errors caused by positioning deviations from the outset and providing an accurate target area benchmark for subsequent secondary ion extraction. Second, the relative positional parameters, such as the distance from the extraction plate to the sample stage, the distance from the extraction chamber to the extraction plate, and the distance from the imaging center to the extraction plate, are determined. This eliminates reliance on experience in determining distance parameters, instead relying on the scientific correlation between optical properties and geometric parameters. This ensures the spatial adaptability of the primary ion beam path and the secondary ion transport path, reducing ion blocking or loss due to improper distance. Finally, based on the quantitatively calculated distance parameters, the extraction chamber, two extraction plates, and the primary ion optical system are installed. This achieves precise spatial coordination between the extraction chamber, extraction plates, and sample beam spot, ensuring the sample center is accurately attacked by the ion beam while most sputtered ions enter the extraction chamber. This constructs an efficient transport path from the sample surface to the extraction chamber, ultimately improving the overall stability and reliability of the secondary ion extraction system and providing a guarantee for high-precision ion analysis. Attached Figure Description

[0021] Figure 1 A structural diagram of the confocal imaging-assisted secondary ion extraction system provided in this application;

[0022] Figure 2 A flowchart of an embodiment of the installation method of the confocal imaging-assisted secondary ion extraction system provided in this application. Detailed Implementation

[0023] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0024] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used herein are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0025] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0026] The following specific embodiments are given to illustrate the technical solution of this application in detail.

[0027] Figure 1 For a structural diagram of the confocal imaging-assisted secondary ion extraction system provided in this application, please refer to... Figure 1 The secondary ion extraction system includes an imaging system and an extraction system, which work together through optical path coupling and mechanical structure positioning. The imaging system is responsible for beam spot monitoring and position calibration, while the extraction system is responsible for the efficient collection and transmission of secondary ions.

[0028] Specifically, the imaging system precisely images the beam spot formed by the ion beam bombarding the sample through an optical path, providing visual guidance for sample stage position adjustment and system calibration. The imaging system includes a CCD, a zoom lens, a beam splitter, a fiber optic light source, a light source support, and a lens support. The CCD, located at the end of the imaging system and the end of the optical path, is fixed by the lens support and coaxial with the zoom lens's optical axis. It is used to acquire beam spot images, convert optical signals into electrical signals, and output digital images for subsequent analysis. The zoom lens is connected in series between the CCD and the beam splitter, with its optical axis aligned with both the CCD and the beam splitter. It is used to adjust the imaging focal length and field of view, ensuring clear and focused beam spot images to accommodate observations of different beam spot sizes. The beam splitter is located at the optical center of the imaging system, installed at a 45° angle to the optical axis. It is used to achieve optical path coupling, i.e., reflecting the incident light from the light source (such as a fiber optic light source) to the sample surface while simultaneously transmitting the beam spot reflected light from the sample surface. The zoom lens allows the imaging light and illumination light to share a single core optical path. The fiber optic light source is mounted on the light source bracket, at the same horizontal plane as the center of the beam splitter, with its incident direction perpendicular to the optical axis of the imaging system. It provides stable illumination light, which is then focused onto the beam spot area on the sample surface after reflection by the beam splitter, enhancing imaging contrast. The light source bracket and lens bracket are used to fix the fiber optic light source and the imaging system (CCD, zoom lens, beam splitter) respectively, ensuring the stability of the optical components and providing mechanical support for optical path calibration.

[0029] The extraction system is responsible for carrying the sample, transmitting the ion beam, extracting secondary ions, and providing the observation target (beam spot) for the imaging system. It mainly includes a primary ion optical system, sample stage, extraction plate, extraction cavity, reflecting spherical mirror, and electron gun. The electron gun works in conjunction with the primary ion optical system to assist in ion beam focusing and sample surface charge control. See also Figure 1The following will describe the positional relationships of the components from the perspectives of horizontal and vertical spatial arrangement, as well as the front view (a front view along the ion beam propagation direction) and top view (a view from above). Specifically, the extraction system uses the ion beam propagation path (the mechanical central axis running horizontally through the system) as its core reference, and the components are precisely arranged around this axis in both horizontal and vertical directions to achieve the synergy of sample carrying, ion transport, secondary ion extraction, and imaging assistance functions. The primary ion optical system is installed at the front end of the extraction system. In the main view, it is arranged horizontally, with the ion beam emission direction (horizontally to the right) facing the sample stage. The optical center must coincide with the mechanical center of the extraction system. It is used to emit a high-energy ion beam to bombard the sample surface and generate a beam spot, serving as the source of the beam current. The electron gun is installed at an angle to the side of the primary ion optical system (which can be shown in the main view as forming a preset angle with the horizontal direction, such as 45°). Its emission direction points towards the center area of ​​the sample stage, where it intersects with the ion beam of the primary ion optical system on the sample surface. It assists in ion beam focusing or participates in sample pretreatment processes. The relative positions of the two systems, through their synergy in the sample interaction area, ensure stable beam spot generation. In addition, the current value of the electron gun needs to be determined based on the sputtered secondary ion signal. Specifically, the electron gun current depends on the charge neutralization effect. When bombarding the sample with an ion beam, the sputtered secondary ion signal is scanned in real time. The electron gun current intensity value is calculated based on the electron gun current intensity constraint and the secondary ion signal intensity. The electron gun is set according to the current intensity value so that the electron gun emits a current of the magnitude of the current intensity value. Thus, it is necessary to first ensure that the electron gun current intensity itself does not generate secondary ions, and secondly, to ensure that the extraction efficiency of secondary ions generated by the primary sputtering reaches the maximum.

[0030] The sample stage is located in front of the exit end of the primary ion optical system. In the top view, it is positioned near the front of the system (corresponding to the ion beam incident side). The sample surface is perpendicular to the ion beam path; that is, in both the front and top views, the sample surface is horizontal. The ion beam is incident along the horizontal mechanical central axis and serves as the carrier for beam spot formation, supporting the sample to be analyzed. It can be moved in the X, Y, and Z directions via a drive mechanism (such as a precision guide rail) to adjust the sample position so that the beam spot center coincides with the sample center. The extraction plate is positioned on the movement path before the beam spot enters the extraction chamber (between the sample and the extraction chamber). In both the front and top views, it is parallel to the sample surface (horizontally), with its central axis coaxial with the central axis of the extraction chamber opening. It is used to filter stray ions, allowing only secondary ions in the beam spot region to pass through, reducing background interference, and its opening size matches the beam spot. The extraction cavity is located in the beam emission direction (behind the sample stage, in the top view, on the side of the sample stage away from the primary ion optical system), with its opening facing the sample (horizontally to the left in the front view, directly opposite the sample stage). In the front view, reflecting spherical mirrors are installed on both sides of the extraction cavity (vertically up and down or horizontally left and right, combined layout as horizontal sides). The reflecting spherical mirrors include a first reflecting spherical mirror and a second reflecting spherical mirror, which are installed in pairs on both sides of the extraction cavity. The spherical reflection characteristics assist the imaging system in determining the position of the imaging focal point, providing an optical reference for beam center positioning and distance calculation. The extraction cavity can integrate auxiliary transmission components such as deflection plates and electrostatic lenses (in the front view, the deflection plates can be vertically distributed on both sides of the ion beam path, and the electrostatic lenses are arranged along the horizontal mechanical central axis) to constrain the transmission path of secondary ions, reduce ion loss, improve extraction efficiency, and have an opening near the sample side to facilitate the reception of secondary ions screened by the extraction plate.

[0031] Example 1

[0032] Figure 2 This is a flowchart of an embodiment of the installation method for the confocal imaging-assisted secondary ion extraction system provided in this application. Please refer to... Figure 2 The installation method includes:

[0033] S201. The ion beam emitted by the primary ion optical system bombards the sample, and the imaging system acquires a beam spot imaging image. Based on the imaging image, the sample stage position is automatically adjusted so that the center of the ion beam spot coincides with the center of the sample.

[0034] It should be noted that, through visual feedback from the imaging system and automatic adjustment of the sample stage, the center of the beam spot formed by the ion beam bombardment of the sample is completely aligned with the center of the area to be analyzed in the sample. This lays the foundation for maximizing subsequent ion extraction efficiency and improving analytical accuracy. Specifically, this process includes ion beam bombardment of the sample, acquisition of beam spot imaging images by the imaging system, image recognition and offset analysis, and sample stage adjustment.

[0035] In practice, the system's primary ion optics system emits a high-energy ion beam. The ion beam propagates along a preset path and bombards the sample surface supported by the sample stage. During the bombardment, the ion beam interacts with the sample surface, forming an energy-concentrated region, i.e., a beam spot (the size and shape of the beam spot are determined by the focusing performance of the ion optics system). At this time, the imaging system is simultaneously activated to capture real-time images of the beam spot on the sample surface through the optical path. Specifically, the illumination light emitted by the fiber optic source is reflected by a beam splitter and focused on the beam spot region, enhancing the contrast between the beam spot and the sample background. The light signal reflected from the beam spot is transmitted through the beam splitter and enters the CCD through a zoom lens to be converted into a digital image. In the image, the beam spot region (with brightness or grayscale different from the surrounding area) and the sample region (including sample edges or preset markings) can be clearly distinguished. Then, the system automatically identifies the beam spot imaging center and the sample center from the image using an image algorithm and calculates the offset. Finally, based on the offset, the precision drive mechanism of the sample stage is driven to move and complete the self-adjustment of the sample stage.

[0036] It should be noted that before automatically adjusting the sample stage position based on the imaging image to make the beam spot center of the ion beam coincide with the sample center, the process further includes:

[0037] (1) Adjust the optical center of the imaging system to be on the same horizontal plane as the mechanical center of the extraction system.

[0038] Specifically, the height of the lens support of the imaging system and the height of the mounting base of the extraction system can be adjusted using a high-precision level to ensure that the optical center of the imaging system (such as the center of the beam splitter or the midpoint of the optical axis of the zoom lens) and the mechanical center of the extraction system (such as the line connecting the center of the sample stage and the center of the extraction cavity opening) are on the same horizontal plane. During calibration, the height difference between the two centers must be measured multiple times until the error (processing and assembly accuracy) is controlled within a preset range (e.g., all less than or equal to 100µm). This eliminates vertical offset between the imaging and extraction systems, ensuring that their core working areas are spatially coplanar and preventing the subsequent imaging field of view from cutting off the mechanical center area due to height differences; for example, the beam spot may extend beyond the imaging range.

[0039] (2) Adjust the installation angle and position of the CCD, zoom lens and beam splitter to keep the optical axis of the imaging system aligned with the mechanical center axis of the extraction system.

[0040] It should be noted that a calibration laser can be emitted using a laser collimator, propagating along the mechanical central axis of the extraction system. Then, by adjusting the mounting angles of the CCD and zoom lens (such as rotating the lens bracket) and the tilt angle of the beam splitter (generally 45° to ensure precise optical path steering), the laser passes sequentially through the center of the beam splitter and the center of the zoom lens, and finally enters the photosensitive center of the CCD. The position of the laser spot on the CCD is fed back, and the positions of the components are fine-tuned until the laser spot is completely aligned with the center of the CCD. At this point, the optical axis of the imaging system is aligned with the mechanical central axis of the extraction system.

[0041] This ensures that the visual line of sight of the imaging system is coaxial with the ion beam path and secondary ion transport path of the extraction system, and that the geometric center in the imaging image corresponds perfectly with the actual mechanical center. This avoids misjudgment of position caused by image offset or distortion, and provides a prerequisite for accurate positioning in subsequent beam spot imaging.

[0042] (3) Adjust the horizontal position of the fiber optic light source and the beam expander so that the incident light is focused on the mechanical center after being reflected by the beam splitter.

[0043] Specifically, the fiber optic light source is turned on, and the beam is expanded into parallel or converging light by a beam expander. Then, the light source support is moved horizontally (by adjusting screws or guide rails) to adjust the focal length of the beam expander so that the incident light is reflected by the beam splitter and forms a clear focused spot at the mechanical center of the extraction system. Finally, the focusing effect is observed in real time through the imaging system until the illumination brightness of the mechanical center area is uniform and there is no difference between light and dark.

[0044] This step ensures sufficient and uniform illumination in the central area of ​​the machine, enhances the contrast between the beam spot and the sample background, and avoids blurred beam spot imaging due to insufficient illumination, which would affect the accuracy of subsequent center identification. In addition, it can also make the reflected light path of the beam splitter precisely coupled with the imaging light path, ensuring that the illumination light and the imaging light share the same core path and reduce optical loss.

[0045] (4) Observe the mechanical center mark through the imaging field of the imaging system until the mark is located at the center of the imaging image.

[0046] It should be noted that physical markers (such as cross lines or circular reference points on the sample stage) can be set at the mechanical center of the extraction system. Then, the CCD of the imaging system can be used to acquire the marker image in real time, observe the position of the marker in the imaging field of view, and finally fine-tune the horizontal position of the lens support of the imaging system until the geometric center of the marker completely coincides with the center of the imaging image. Record the correspondence between the image coordinates and the mechanical coordinates at this time.

[0047] Through the above-mentioned multi-dimensional calibration of the horizontal plane, axis, illumination, and field of view, visual deviations caused by misalignment between the imaging system and the extraction system are fundamentally avoided, ensuring that the optical center of the imaging system and the mechanical center of the extraction system are completely aligned, thus ensuring the authenticity and reliability of subsequent adjustment results.

[0048] It should also be noted that before automatically adjusting the sample stage position based on the imaging image to make the beam spot center of the ion beam coincide with the sample center, the process further includes:

[0049] (1) Install the lens bracket of the imaging system at the preset interface position of the extraction system, and adjust the vertical direction of the lens bracket so that the optical axis of the imaging system and the mechanical central axis of the extraction system are aligned in the vertical direction.

[0050] Specifically, the lens bracket of the imaging system can be aligned with the preset mechanical interface (such as positioning pin hole or guide rail slot) of the extraction system, and the initial position can be fixed by bolts or buckles; then the vertical height of the bracket can be adjusted by using the height adjustment knob (or piezoelectric fine adjustment device), while using a laser interferometer or precision level to monitor the relative position of the optical axis of the imaging system (such as the line connecting the center of the zoom lens) and the mechanical central axis of the extraction system (the line connecting the center of the sample stage to the center of the extraction cavity opening) in the vertical direction until the two are on the same vertical line.

[0051] It should be noted that in this step, the mechanical connection between the imaging system and the extraction system can be quickly achieved through the preset interface, reducing the randomness of installation. Furthermore, the vertical axis alignment ensures that the core working paths of both systems are not offset in the vertical direction, avoiding the obstruction of beam spot imaging or the deviation of the extraction system's receiving range from the beam spot area due to vertical misalignment.

[0052] (2) Install the beam splitter at a preset angle in the lens bracket and adjust its position so that the center of the beam splitter coincides with the optical axis of the imaging system.

[0053] Fix the beam splitter in the lens holder's slot at a preset angle (usually 45°, to accommodate optical path turning requirements). Move the beam splitter using the fine-tuning screws on the holder, while simultaneously emitting a calibration laser that propagates along the optical axis of the imaging system. Observe whether the laser paths after reflection and transmission through the beam splitter are symmetrical. If the reflected and transmitted light propagate along preset directions and have uniform energy, it indicates that the center of the beam splitter coincides with the optical axis. Here, aligning the center of the beam splitter with the optical axis of the imaging system ensures that the optical path is not off-center, avoiding image distortion or uneven brightness.

[0054] (3) Install the light source bracket at a horizontal position corresponding to the center of the beam splitter, and adjust the height and angle of the light source bracket so that its installation direction is perpendicular to the lens bracket.

[0055] Specifically, using the center of the beam splitter as a reference, the installation position of the light source bracket is determined horizontally (using a ruler or positioning block). After fixing, the bracket height is adjusted so that the center of the fiber optic light source and the beam expander is at the same height as the center of the beam splitter. Then, the light source bracket is rotated, and its installation direction is confirmed to be perpendicular to the lens bracket using a protractor or laser perpendicularity meter. Finally, the beam emitted by the light source is horizontally incident on the center of the beam splitter after beam expansion. Here, horizontal position and height calibration ensure that the incident light accurately illuminates the beam splitter, avoiding the reflected light from failing to focus on the mechanical center due to offset. In addition, vertical installation reduces stray light interference, ensuring the stability and consistency of illumination.

[0056] After completing the above operations, the sample stage position is automatically adjusted according to the imaging image so that the beam spot center of the ion beam coincides with the sample center, including:

[0057] (1) Identify the beam spot imaging center from the imaging image.

[0058] It should be noted that the beam spot images acquired by the imaging system can be processed using image algorithms. First, the image is denoised (e.g., Gaussian filtering) and contrast enhanced to highlight the difference between the beam spot region and the background. Then, a threshold segmentation method is used to extract the contour boundary of the beam spot, or the gray-weighted center coordinates of the beam spot region (i.e., the beam spot imaging center) are calculated using the gray-level centroid method. For irregular beam spots, edge detection algorithms can be combined to optimize the contour extraction accuracy.

[0059] (2) Identify the sample center from the imaging image.

[0060] Specifically, the matching recognition algorithm can be selected based on the characteristics of the sample. If the sample surface has preset marks (such as cross lines or circular reference points), the center of the marks can be located as the sample center using template matching. If the sample is a regular shape (such as a circle or rectangle), the sample contour can be extracted through edge detection, and then the geometric center of the contour can be calculated (such as the center of the smallest circumcircle or the intersection of the diagonals of a rectangle). In addition, for samples without obvious features, the analysis center can be determined by combining the user-preset region of interest (ROI). In this way, the positioning needs of different types of samples can be adapted, ensuring the flexibility and accuracy of sample center identification.

[0061] (3) The sample stage is moved according to the offset direction and offset distance between the beam spot imaging center and the sample center. The moving direction of the sample stage is opposite to the offset direction, and the moving distance of the sample stage is proportional to the offset distance.

[0062] It should be noted that the image offset between the beam spot imaging center and the sample center is converted into an actual physical offset (e.g., micrometers) through coordinate transformation, and the offset direction (e.g., positive X-axis direction, negative Y-axis direction) and offset distance are determined. The control system sends a command to the drive mechanism of the sample stage based on the offset data, driving the sample stage to move in the opposite direction to the offset direction. The moving distance is equal to the physical offset (or finely adjusted according to a preset ratio). After the movement, the image is acquired a second time by the imaging system for verification until the center deviation between the two is less than a preset threshold.

[0063] Specifically, the image acquired by the imaging system is first analyzed at the pixel level to identify the position of the beam spot imaging center and the sample center in the image coordinate system. If the beam spot imaging center is to the left relative to the sample center (e.g., in the horizontal X-axis direction, the x-coordinate of the beam spot center is smaller than the x-coordinate of the sample center), the sample stage is moved along the positive X-axis direction (to the right); if it is to the right (the x-coordinate of the beam spot center is larger than the x-coordinate of the sample center), the sample stage is moved along the negative X-axis direction (to the left). The same logic applies to the vertical Y-axis direction: if the beam spot center is higher (the y-coordinate is larger than the y-coordinate of the sample center), the sample stage is moved along the negative Y-axis direction (downward); if it is lower (the y-coordinate is smaller than the y-coordinate of the sample center), it is moved along the positive Y-axis direction (upward).

[0064] Simultaneously, using the optical parameters of the imaging system (such as magnification and pixel-to-actual-size), the offset pixel values ​​in the image are converted into actual physical offset distances (e.g., in micrometers). Since the sample stage movement distance is proportional to the offset distance, if the beam spot diameter is D1 and the sample region of interest diameter is d1, to ensure the sample region of interest completely covers the beam spot's effective range, the physical offset distance can be fine-tuned proportionally by k (k=d1 / D1, k≥1 when d1≥D1), making the sample stage movement more adaptable to actual analytical needs. After movement, images are acquired again through the imaging system for verification until the center deviation between the two is less than a preset threshold (e.g., 1 / 10 of the beam spot diameter), ensuring the beam spot accurately acts on the sample analysis area.

[0065] In this step, automatic identification and adjustment through algorithms can avoid the subjectivity and fatigue errors of manual positioning, improve the automation level of the system, and ensure that the beam spot and the sample center are precisely aligned, so as to ensure that the ion beam bombardment area and the sample to be analyzed are completely matched, reducing the deviation of analytical data caused by misalignment.

[0066] S202. Determine the first distance from the sample stage to the extraction plate and the second distance from the extraction cavity to the extraction plate.

[0067] It should be noted that the first distance is the distance from the center of the sample spot to the extraction plate, such as... Figure 1As shown in the view direction, the first distance refers to the horizontal distance from the sample stage to the extraction plate. The spherical mirror parameters of the reflecting spherical mirror include the radii of curvature (denoted as R1 and R2) of the first and second reflecting spherical mirrors located on both sides of the extraction cavity, as well as the distance between the two reflecting spherical mirrors (denoted as D). These parameters are the basis for determining the spatial position of the imaging focal point, which is the reference for the beam propagation direction.

[0068] It should be noted that the second distance refers to the spatial distance between the extraction chamber and the extraction plate. The opening radius of the extraction chamber near the sample side refers to the geometric parameter of the extraction chamber inlet, which determines the spatial range within which the chamber receives secondary ions. The larger the radius, the wider the theoretical receiving range, but it must match the opening of the extraction plate. The opening radius of the extraction plate refers to the size of the opening on the extraction plate that allows secondary ions to pass through. It is the channel for secondary ions to enter the transmission path, and its size and the fit between the opening radius of the extraction plate directly affect the unobstructed transmission.

[0069] It should be noted that the determination of the first and second distances, as well as the thickness of the extraction plate, must be based on preventing high-voltage discharge as the core constraint. This must be combined with the breakdown characteristics under high-voltage and vacuum conditions to ensure that the electric field strength between components does not exceed a safe threshold. Specifically, from the perspective of high-voltage discharge protection principles, during system operation, there is a preset high-voltage difference between the extraction plate and the sample stage (used to drive secondary ions to detach from the sample surface), and there is also a high-voltage difference between the extraction plate and the interior of the extraction chamber (used to constrain the direction of secondary ion transport). In a vacuum environment, air has a breakdown field strength, and the extraction plate also has a breakdown field strength (related to the material of the extraction plate). If the component spacing or plate thickness is too small, the local electric field strength may exceed the breakdown field strength, triggering high-voltage discharge. This not only interferes with the ion transport path but may also damage equipment components.

[0070] Therefore, the determination of the first distance must simultaneously meet the dual requirements of unobstructed ion beam and anti-discharge. First, based on the incident diameter of the ion beam and the minimum opening diameter of the extraction chamber, calculate the theoretical distance to ensure that the ion beam completely covers the opening of the extraction plate. Then, calculate the minimum anti-discharge distance using the formula L1 safety = ΔU / (0.8 × Ebreak) (ΔU is the high voltage difference between the sample stage and the extraction plate, 0.8 is a coefficient for reserving a 20% safety margin, which can be set according to actual needs, and Ebreak is the vacuum breakdown field strength). Finally, take the larger value of the two as the first distance to avoid discharge caused by insufficient spacing.

[0071] The determination of the second distance needs to balance the loss of secondary ion diffusion and the prevention of discharge. First, based on the diffusion half angle of secondary ions and the opening size of the extraction chamber, calculate the theoretical maximum distance to ensure that the ions completely enter the chamber after diffusion. Then, calculate the minimum distance to prevent discharge using the formula L2 safety = ΔU' / (0.8 × Ebreak) (ΔU' is the high voltage difference between the extraction plate and the extraction chamber). If the safe distance is less than or equal to the theoretical maximum distance, take the middle value (considering both efficiency and safety). If the safe distance exceeds the theoretical maximum distance, the high voltage difference needs to be reduced or the chamber opening needs to be enlarged, and the parameters need to be readjusted.

[0072] Determining the thickness of the plate requires matching the total high voltage difference on both sides. The minimum thickness is calculated using the formula h≥(ΔU+ΔU') / Ebreak plate (Ebreak plate is the breakdown field strength of the plate material) to ensure that the plate itself is not broken down. At the same time, the thickness needs to be controlled to avoid excessive energy loss in ion transmission inside the plate due to excessive thickness, so as to achieve a synergy between anti-discharge and ion transmission efficiency.

[0073] Furthermore, it should be noted that the calculation of the first distance also includes establishing a three-dimensional coordinate system based on the geometric distance from the imaging focal point to the center of the first and second reflecting spherical mirrors, where the center of the first reflecting spherical mirror is the origin and the line connecting the centers of the two reflecting spherical mirrors is the Z-axis; substituting the installation position parameters and opening geometric parameters of the extraction plate into the coordinate system; calculating the intersection of the beam path and the opening of the extraction plate according to the preset incident angle and beam propagation direction of the primary ion beam to obtain the incident point; and calculating the spatial straight-line distance from the center of the sample surface beam spot to the incident point in the coordinate system as the first distance.

[0074] Based on the preceding description, if the coordinates of the sample surface spot center coincide with the sample center, denoted as (x... s y s , z s ) and the coordinates of the incident point (denoted as (x i y i , z i Along the beam propagation direction (i.e., the direction of the line connecting the two points), the straight-line distance is calculated using the spatial distance formula. The first distance is then equal to... .

[0075] The calculation of the second distance includes:

[0076] (1) Under the condition that the central axis of the extraction plate is coaxial with the central axis of the extraction cavity near the sample side opening, the value of the first distance, the radius of the extraction cavity near the sample side opening and the opening radius of the extraction plate are obtained.

[0077] It should be noted that the relative positions of the extraction plate and the extraction chamber can be adjusted using a laser collimator or precision mechanical positioning tools to ensure that the central axis of the extraction plate (the line connecting the centers of the openings) is completely aligned with the central axis of the extraction chamber opening near the sample (with coaxiality error controlled within the micrometer level), thus ensuring that the secondary ion transport path is unobstructed. Then, the previously calculated first distance value is obtained, and the opening radius of the extraction chamber (the inlet radius near the sample) and the opening radius of the extraction plate are measured using precision measuring instruments, and the measured data are recorded.

[0078] (2) Establish the nonlinear correlation equation between the second distance and the first distance, the extracted cavity opening radius, and the extracted plate opening radius.

[0079] Specifically, an optical transport model for secondary ion extraction efficiency (such as Monte Carlo simulation or geometric optics tracking model) can be used to simulate the spatial transport trajectory of secondary ions after they are ejected from the opening of the extraction plate. After leaving the opening, the ions will spread outward due to the initial velocity distribution, and the divergence angle is positively correlated with the first distance (the larger the first distance, the wider the lateral diffusion range of the ions when they reach the extraction plate).

[0080] Furthermore, based on the model simulation results, a correlation equation was established between the second distance and the first distance, the extraction cavity opening radius, and the extraction plate opening radius. The calculation factor of the second distance increases non-linearly with the increase of the first distance, and adjusts stepwise with the ratio of the extraction cavity opening radius to the extraction plate opening radius.

[0081] (3) Substitute the measured parameters of the first distance, the radius of the cavity opening, and the radius of the plate opening into the nonlinear correlation equation to obtain the value of the second distance.

[0082] Substitute the measured parameters of the first distance, the radius of the extraction cavity opening, and the radius of the extraction plate opening obtained in step (1) into the nonlinear correlation equation, and solve for the value of the second distance using a numerical calculation method. Then, based on the solved value of the second distance, simulate the transmission trajectory of secondary ions in reverse using an optical transmission model to check whether there are ion collisions with the edge of the extraction plate or the edge of the cavity opening; if there is obstruction, fine-tune the parameters and solve again until all trajectories are unobstructed from the center of the opening to the center of the cavity opening.

[0083] S203. Calculate the third distance from the imaging focal point of the secondary ion extraction system to the sample stage based on the spherical mirror parameters of the reflecting spherical mirror.

[0084] The imaging focus is the imaging point located on the side of the extraction chamber with a relatively larger diameter where the ions from the secondary sputtering are output after passing through the extraction chamber. An image of this imaging point is acquired by a CCD camera or similar device in the secondary ion extraction system. From... Figure 1As shown in the view, the third distance is the horizontal distance from the imaging focal point to the sample stage, and the third distance has a non-linear relationship with the spherical mirror parameters.

[0085] Specifically, the third distance from the imaging focal point of the secondary ion extraction system to the sample stage is calculated based on the spherical mirror parameters of the reflecting spherical mirror, including:

[0086] (1) Obtain the radius of curvature of the first and second reflecting spherical mirrors located on both sides of the extraction cavity and the distance between the first and second reflecting spherical mirrors.

[0087] It should be noted that the curvature radii (denoted as R1 and R2) of the first and second reflecting spherical mirrors can be obtained through the system design drawings, and the actual distance (denoted as D) between the centers of the two reflecting spherical mirrors can be measured using precision measuring tools. During the measurement, it is necessary to ensure that the center of the sphere is accurately positioned (the position of the center of the sphere can be determined by fitting the curvature of the spherical mirror surface or by setting a preset positioning mark).

[0088] It should be noted that the radius of curvature determines the optical focusing characteristics of the reflecting sphere, and the spacing reflects the spatial distribution of the two spheres. Accurate measurement of both can avoid the failure of subsequent distance calculations due to parameter errors.

[0089] (2) Based on the radius of curvature and the spacing, establish the imaging geometric relationship, calculate the geometric distance from the imaging focal point to the center of the first reflecting spherical mirror and the center of the second reflecting spherical mirror, and determine the spatial position of the imaging focal point.

[0090] Specifically, calculating the geometric distance from the imaging focal point to the center of the first reflecting spherical mirror includes: calculating the product of the radii of curvature of the first reflecting spherical mirror and the second reflecting spherical mirror; calculating the sum of the difference in the radii of curvature between the first reflecting spherical mirror and the second reflecting spherical mirror and the distance between them; and determining the ratio of the product to the sum as the geometric distance from the imaging focal point to the center of the first reflecting spherical mirror.

[0091] It should be noted that, based on the principles of optical imaging, a geometric relationship is established between the reflecting spherical mirror and the imaging focal point. The distance Z0 from the imaging focal point to the center of the first reflecting spherical mirror is calculated using the formula based on the radii of curvature R1 and R2 of the two spherical mirrors and the distance D between them. The specific formula is as follows:

[0092] ;

[0093] Then, the distance Z1 from the focal point to the center of the second reflecting sphere is calculated according to Z1=D-Z0 (or adjusted according to the actual geometric relationship).

[0094] Furthermore, a three-dimensional coordinate system can be established with the center of the first reflecting spherical mirror as the origin and the line connecting the two centers as the Z-axis. Z0 and Z1 can be converted into the coordinates of the focal point to clarify its precise position in space.

[0095] (3) Based on the imaging focal point, determine the beam propagation direction by combining the preset incident angle of the primary ion beam, and determine the center position of the primary ion beam spot on the sample surface according to the installation position of the extraction plate and the geometric parameters of its opening.

[0096] Specifically, using the imaging focal point as a reference and combining the preset incident angle of the primary ion beam (usually along the central axis of the system), the spatial propagation path of the beam is determined. In a three-dimensional coordinate system, this is represented by the equation of a straight line starting from the center of the beam spot on the sample surface and passing through the extension line of the imaging focal point. Substituting the installation position parameters of the extraction plate (such as horizontal coordinates) and the aperture geometric parameters (such as aperture center and radius) into this straight line equation, the coordinates of the intersection point between the straight line and the plate plane are calculated. If the intersection point is within the aperture range, it means that the beam can pass through the aperture without obstruction. The straight line is then extended towards the sample side, and the intersection point with the sample stage surface is the position of the beam spot center. For details of this process, please refer to the description of relevant technologies, which will not be repeated here.

[0097] (4) Calculate the horizontal straight-line distance from the imaging focal point to the center of the beam spot along the reverse extension line of the beam propagation direction, and use it as the third distance.

[0098] Specifically, based on the preceding description, along the opposite direction of the beam propagation direction (a horizontal straight line extending from the imaging focus to the sample stage), the horizontal straight line distance calculated by substituting the imaging focus coordinates and the beam spot center coordinates determined in step (3) into the distance formula between two points in space is the third distance.

[0099] S204. Calculate the relative distance between the extraction cavity and the extraction plate based on the difference between the third distance and the first and second distances.

[0100] It should be noted that the relative distance is the distance from the horizontal line of the short side of the extraction cone to the imaging focal point. Specifically, the relative distance between the extraction cavity and the extraction plate is calculated based on the difference between the third distance and the first and second distances. In practice, the thickness parameter of the extraction plate also needs to be considered. In the specific implementation, if the first distance is represented by L1, the second distance by L2, the third distance by L3, and the thickness of the extraction plate by h, then the relative distance D1 = L3 - L1 - L2 - h.

[0101] In conjunction with the foregoing description, it should also be noted that the extraction cavity is a combination of a cylinder and a frustum, placed on a horizontal track. The extraction cavity includes a first opening and a second opening. The first opening is close to the extraction plate, and the second opening is close to the imaging focal point. The diameter of the first opening is larger than the diameter of the second opening, and the diameter of the first opening is the same as the opening diameter of the two oppositely positioned extraction plates. The sum of the ion beam incident diameter of the primary ion optical system and the first distance is equal to the minimum radius of the extraction cavity. The extraction plate is installed at the cavity port, and the extraction cone, deflection plate, electrostatic lens, and spherical mirror frame and spherical mirror of the imaging system are fixedly installed inside.

[0102] It should be noted that the conical structure can guide the transport direction of secondary ions through geometric constraints, reducing diffusion losses in the early stages of ion transport and mitigating the risk of edge occlusion. This allows more secondary ions to converge into the cavity, laying the structural foundation for subsequent efficient extraction. The larger the radius of curvature of the reflecting spherical mirror and the smoother its surface, the longer the propagation path of the primary ion beam after reflection (the focal point is further out), resulting in an increased distance (first distance) from the center of the beam spot on the sample surface to the incident point on the extraction plate. The imaging focal point is the point where the primary ion beam focuses on the sample surface. The greater this distance, the longer the propagation path of the primary ion beam from the spherical mirror to the sample, thus increasing the first distance.

[0103] In addition, the installation method provided in this application also includes:

[0104] (1) Obtain the diameter of the ion beam emitted by the primary ion optical system.

[0105] It should be noted that the ion beam diameter is a core prerequisite parameter determining the minimum opening size of the conical cavity, and its value must be obtained through direct measurement or system parameter retrieval. Direct measurement involves using beam diagnostic equipment (such as a Faraday cup or laser interferometer) to measure the ion beam emitted by the primary ion optical system. System parameter retrieval means that if the ion beam emission diameter parameter is clearly specified in the primary ion optical system's technical manual, this value can be directly retrieved as an initial reference. If the system supports software control of the beam spot size, the primary ion optical system must first be adjusted to the required beam mode, and then the ion beam diameter in the current mode must be read from the system control software to ensure consistency with the actual beam spot size of the sample being bombarded.

[0106] It is important to note that the ion beam diameter is affected by parameters such as accelerating voltage and focusing lens current. Therefore, the corresponding system operating parameters must be recorded when measuring or retrieving the data. If these parameters are adjusted during subsequent installation, the ion beam diameter must be obtained again to avoid occlusion problems caused by parameter mismatch.

[0107] (2) Solve the numerical relationship between the diameter of the ion beam and the first distance and the minimum opening diameter of the conical cavity based on the constraints of the ion beam bombardment path.

[0108] Specifically, the numerical relationship between the diameter of the ion beam and the first distance, and the minimum opening diameter of the conical cavity, is solved based on the constraints of the ion beam bombardment path, including:

[0109] (i) Construct a geometry with the ion beam exit point at the extraction plate and the center of the sample stage as vertices based on the constraint condition of the ion beam bombarding the center of the sample stage, wherein one side of the geometry is the first distance.

[0110] Using the system's mechanical central axis (the core path of ion beam propagation) as a reference, and combining the definition of the first distance (the horizontal distance from the sample stage to the extraction plate), an isosceles triangle geometric model is constructed. The base of the triangle represents the distance between the ion beam exit points at the opening of the extraction plate. Since the ion beam must pass perpendicularly through the opening of the extraction plate, and the center of the opening is coaxial with the system's mechanical central axis, the exit point of the ion beam on the extraction plate is the center of the opening. Its projected width perpendicular to the beam propagation direction (horizontal transverse direction) is equal to the ion beam diameter.

[0111] The height of the triangle represents the first distance, which is the horizontal straight-line distance from the center of the sample stage (the ion beam bombardment point) to the exit point of the extraction plate. This distance has been calculated and determined through step S202 and is completely consistent with the ion beam propagation direction. The two sides of the triangle represent the edge propagation path of the ion beam, extending in a straight line from the center of the sample stage (the edge of the beam spot) to the edge of the opening of the extraction plate (the edge of the exit point). The extension lines of the two sides must completely cover the minimum opening range of the conical cavity to ensure that the secondary ions generated after the ion beam bombards the sample can enter the cavity without obstruction along this path.

[0112] In addition, if the ion beam has a small divergence angle, the divergence angle must be taken into account when constructing the geometry to avoid actual transmission obstruction caused by ignoring the divergence.

[0113] (ii) Calculate the numerical relationship based on the numerical relationship between the side lengths of the geometric shape.

[0114] It should be noted that the smallest opening of the conical cavity (located on the side of the extraction plate near the cavity) is regarded as the base of a large isosceles triangle. This large triangle is similar to the small isosceles triangle constructed in step (i) (with the ion beam diameter as the base and the first distance as the height). The two triangles share a common vertex (the center of the sample stage), and the waists of the two triangles extend along the propagation path of the ion beam edge. Therefore, the corresponding side lengths are proportional.

[0115] Let the base of the small triangle be d (ion beam diameter) and its height be L1 (first distance); let the base of the large triangle be D. min (Minimum opening diameter of the conical cavity), height is L1 + L2 (where L2 is the horizontal distance from the extraction plate to the minimum opening of the conical cavity; since the thickness of the extraction plate is much smaller than L1, we can approximate L2≈0, meaning the height of the large triangle is approximately equal to L1). Based on the proportional relationship of the side lengths of similar triangles... If the divergence angle α of the ion beam is considered, the height of the large triangle needs to be corrected to L1 + ΔL (ΔL is the actual distance from the extraction plate to the minimum opening of the cavity). At this point, the proportional relationship is adjusted to... Further organization yields numerical relationships. This relationship indicates that the minimum opening diameter of the conical cavity needs to increase with the increase of the ion beam diameter and the lengthening of the first distance to ensure that the edge and diverging part of the ion beam can completely enter the cavity without lateral obstruction.

[0116] (3) Substitute the first distance and the diameter of the ion beam into the numerical relationship to calculate the minimum opening diameter of the conical cavity.

[0117] Taking a real installation scenario as an example, if the measured ion beam diameter is 20μm, the first distance is 10mm, and the distance from the extraction plate to the minimum opening of the cavity is 5mm, then the minimum opening diameter of the conical cavity is 30μm.

[0118] Furthermore, the larger the aperture radius of the extraction plate, the wider the diffusion range after secondary ion emission. To prevent diffused ions from being blocked by the edges of the extraction chamber, the distance between the extraction chamber and the plate (the second distance) needs to be increased to accommodate a larger range of ion transport. The larger the cavity opening radius, the wider its receiving range. To match this larger receiving range, the second distance needs to be increased to ensure that ions diffused from the plate aperture can more fully enter the cavity and reduce edge loss.

[0119] It should also be noted that the nonlinear relationship means that the second distance does not increase linearly with the parameters, but rather exhibits a sudden increase in the rate of increase. The stepwise increase means that when the first distance increases to a certain threshold (or the cavity opening radius increases to a certain threshold), the growth rate of the second distance will suddenly accelerate. This is because when the parameters exceed the threshold, the risk of ion transport obstruction or the efficiency requirements will change dramatically (for example, the diffusion range suddenly exceeds the capacity of the original distance), and the transport efficiency must be maintained by increasing the second distance more rapidly.

[0120] S205. Install the extraction cavity according to the relative distance.

[0121] In practical implementation, the spatial coordinates of the extraction cavity are determined based on the system's preset three-dimensional coordinate system (with the center of the first reflecting spherical mirror as the origin, the line connecting the centers of the two reflecting spherical mirrors as the Z-axis, the horizontal direction perpendicular to the Z-axis as the X-axis, and the vertical direction as the Y-axis). This is combined with the relative distances calculated from the differences between the third distance and the first and second distances in S204. Specifically, the third distance is the horizontal distance from the imaging focal point to the sample stage (determined by calculation in S203), the first distance is the horizontal distance from the sample stage to the extraction plate (determined by calculation in S202), and the second distance is the horizontal distance from the extraction cavity to the extraction plate (determined by calculation in S202). Furthermore, the thickness parameter of the extraction plate must be included for correction.

[0122] During installation, the extraction chamber is moved to the calculated coordinate position using a precision guide rail or positioning bracket. First, the extraction chamber is pushed along the Z-axis, and the horizontal position is calibrated in real time using a displacement sensor to match the calculated value of the Z-axis coordinate of the first opening end face. Then, a laser collimator is used to emit a laser that propagates along the mechanical central axis, and the vertical height (Y-axis direction) and horizontal position (X-axis direction) of the extraction chamber are finely adjusted to ensure that the laser can pass through the opening of the extraction plate and the first opening of the extraction chamber in sequence, and the coaxiality error is controlled within the specified value (e.g., 5μm) to avoid ion blocking due to eccentricity.

[0123] In addition, before fixing the extraction chamber, the installation accuracy needs to be confirmed through double verification. First, observe the relative position of the first opening of the extraction chamber and the opening of the extraction plate through the imaging system to ensure that the centers of the two coincide and the edges are unobstructed. Second, start the primary ion optical system to bombard the sample and detect the secondary ion signal intensity through the ion detector inside the extraction chamber. If the signal intensity reaches more than 90% of the theoretical maximum value (set according to actual needs), it indicates that the transmission path is suitable. If there is a deviation, fine-tune the extraction chamber along the Z-axis until the signal intensity is stable.

[0124] The installation method provided in this embodiment achieves efficient collaboration between the imaging and extraction systems through multi-dimensional calibration, precise parameter calculation, and standardized installation procedures. This effectively solves the problems of reference misalignment, empirical parameter reliance, and significant ion transmission loss in existing installation methods. Specifically, through multi-dimensional calibration of the imaging system (alignment of the optical and mechanical centers horizontally, coaxial calibration of the optical and mechanical axes, precise 45° installation of the beam splitter, and focusing of the light source at the mechanical center), combined with image algorithms to automatically identify the beam spot imaging center and the sample center, and drive the sample stage to move precisely in the opposite direction of the offset, the beam spot center is ensured to completely coincide with the center of the sample's analytical area. This provides an accurate target area reference for ion extraction, avoiding analytical area misalignment caused by positioning errors, and improving the accuracy of mass spectrometry analysis from the source. Based on optical parameters such as the radius of curvature of the reflecting spherical mirror and the distance between the two spherical mirrors, the spatial position of the imaging focal point is calculated through imaging geometry. The incident point is determined by combining the preset incident angle of the primary ion beam and the opening parameters of the extraction plate, thereby accurately calculating the first distance. At the same time, the second distance, which is nonlinearly correlated, is calculated by combining the secondary ion diffusion half angle, the opening radius of the extraction cavity, and the high-voltage discharge protection requirements. This allows the determination of the core distance parameters to rely on scientific optical laws, geometric relationships, and high-voltage protection logic, breaking away from the experience-based dependence of traditional installation. This ensures that the primary ion beam passes through the opening of the extraction plate without obstruction and that the secondary ions enter the extraction cavity without diffusion loss.

[0125] Finally, the relative distance is calculated based on the difference between the third distance and the first, second, and extraction plate thicknesses. The extraction cavity is then installed according to this relative distance. The coaxiality is calibrated using a laser collimator, and the installation accuracy is verified by both the imaging system and the ion detector. This achieves precise spatial matching between the extraction cavity, the extraction plate, and the sample beam spot, constructing a complete and efficient transmission path from sample surface sputtering → extraction plate opening → inside the extraction cavity. This effectively reduces diffusion loss and edge occlusion during secondary ion transmission. Combined with the ion confinement effect of the deflection plate and electrostatic lens inside the extraction cavity, the secondary ion extraction efficiency is further improved. At the same time, the standardized installation process ensures consistent system assembly accuracy in different scenarios, significantly improving the equipment's operational stability and repeatability.

[0126] Example 2

[0127] Corresponding to the aforementioned embodiment of the installation method of a confocal imaging-assisted secondary ion extraction system, this application also provides a confocal imaging-assisted secondary ion extraction system.

[0128] Please continue to refer to Figure 1 The system provided in this embodiment includes:

[0129] An imaging system is used to acquire beam spot imaging images of ion beam bombardment of samples and to assist in locating the position of the beam spot center relative to the sample center.

[0130] The extraction system includes an extraction cavity, a reflecting spherical mirror, an extraction plate, a primary ion optical system, and a sample stage;

[0131] The extraction cavity is located in the direction of the ion beam that bombards the sample. The extraction cavity has an opening near the sample side. The extraction cavity is installed with the extraction plate by a relative distance calculated based on the difference between the third distance and the first and second distances.

[0132] The reflecting spherical mirrors are located on both sides of the extraction cavity to cooperate with the imaging system to determine the position of the imaging focal point and to provide spherical mirror parameter support for calculating the third distance from the imaging focal point to the sample stage.

[0133] The extraction plate is positioned on the motion path of the emitted beam spot before it enters the extraction cavity. It has an opening corresponding to the beam spot and is used to determine the first distance in conjunction with the sample stage and the second distance in conjunction with the extraction cavity, providing a positional and geometric parameter reference for the calculation of the relative distance.

[0134] The primary ion optical system is used to emit an ion beam to bombard the sample, the sample stage is used to adjust the sample position so that the beam spot center coincides with the sample center, and the position parameters of the sample stage are used to calculate the first distance from the sample stage to the extraction plate.

[0135] The system in this embodiment is similar in its implementation principle and process, and will not be described again here.

[0136] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for installing a confocal imaging-assisted secondary ion extraction system, the secondary ion extraction system comprising an imaging system and an extraction system, the extraction system comprising an extraction cavity, a reflecting spherical mirror, and an extraction plate, the extraction cavity being disposed in the direction of the emitted beam spot when the ion beam bombards the sample, the reflecting spherical mirror being disposed on both sides of the extraction cavity, and the extraction plate being disposed on the movement path of the emitted beam spot before entering the extraction cavity, and having an opening corresponding to the beam spot, characterized in that... The installation method includes: An ion beam emitted by an ion optics system bombards a sample, and the imaging system acquires a beam spot image. Based on the image, the sample stage position is automatically adjusted so that the center of the ion beam spot coincides with the center of the sample. Determine a first distance from the sample stage to the extraction plate and a second distance from the extraction chamber to the extraction plate; The calculation of the third distance from the imaging focus of the secondary ion extraction system to the sample stage based on the spherical mirror parameters of the reflecting spherical mirror includes: obtaining the radii of curvature of the first and second reflecting spherical mirrors located on both sides of the extraction cavity and the distance between the first and second reflecting spherical mirrors; establishing an imaging geometry relationship based on the radii of curvature and the distance, calculating the geometric distances from the imaging focus to the centers of the first and second reflecting spherical mirrors respectively, and determining the spatial position of the imaging focus; using the imaging focus as a reference, determining the beam propagation direction in combination with the preset incident angle of the primary ion beam, and determining the beam spot center position of the primary ion beam on the sample surface based on the installation position of the extraction plate and the geometric parameters of its opening; calculating the horizontal straight-line distance from the imaging focus to the beam spot center along the reverse extension line of the beam propagation direction, as the third distance; The relative distance between the extraction cavity and the extraction plate is calculated based on the difference between the third distance and the first distance, the second distance, and the thickness of the extraction plate. The extraction cavity is installed according to the relative distance.

2. The installation method according to claim 1, characterized in that, The extraction cavity is conical near the sample side. The extraction cavity includes a first opening and a second opening. The first opening is near the extraction plate, and the second opening is near the imaging focal point. The diameter of the first opening is larger than the diameter of the second opening. The diameter of the first opening is the same as the opening diameter of the two extraction plates that are set up opposite each other. The sum of the ion beam incident diameter of the primary ion optical system and the first distance is equal to the minimum radius of the extraction cavity.

3. The installation method according to claim 1, characterized in that, Calculating the geometric distance from the imaging focal point to the center of the first reflecting spherical mirror includes: Calculate the product of the radii of curvature of the first reflecting spherical mirror and the second reflecting spherical mirror; Calculate the sum of the difference in the radii of curvature between the first and second reflecting spherical mirrors and the distance between them; The ratio of the product to the sum is determined as the geometric distance from the imaging focal point to the center of the first reflecting spherical mirror.

4. The installation method according to claim 1, characterized in that, The method further includes: Obtain the diameter of the ion beam emitted by the primary ion optical system; The numerical relationship between the diameter of the ion beam and the first distance and the minimum opening diameter of the conical cavity is solved based on the constraints of the ion beam bombardment path. Substitute the first distance and the diameter of the ion beam into the numerical relationship to calculate the minimum opening diameter of the conical cavity.

5. The installation method according to claim 4, characterized in that, The step of solving the numerical relationship between the diameter of the ion beam and the first distance and the minimum opening diameter of the conical cavity based on the constraints of the ion beam bombardment path includes: Based on the constraint condition that the ion beam bombards the center of the sample stage, a geometric shape is constructed with the ion beam exit point on the extraction plate and the center of the sample stage as vertices, and one side of the geometric shape is the first distance; The numerical relationship is calculated based on the numerical relationship between the side lengths of the geometric shape.

6. The installation method according to claim 1, characterized in that, The step of automatically adjusting the sample stage position based on the imaging image to make the beam spot center of the ion beam coincide with the sample center includes: Identify the beam spot imaging center from the imaging image; Identify the sample center from the imaging image; The sample stage is moved according to the offset direction and offset distance between the beam spot imaging center and the sample center. The moving direction of the sample stage is opposite to the offset direction, and the moving distance of the sample stage is proportional to the offset distance.

7. The installation method according to claim 1, characterized in that, The imaging system includes a CCD, a zoom lens, and a beam splitter. Before automatically adjusting the sample stage position based on the imaging image to make the beam spot center of the ion beam coincide with the sample center, the system further includes: Adjust the optical center of the imaging system to be on the same horizontal plane as the mechanical center of the extraction system; Adjust the mounting angle and position of the CCD, zoom lens and beam splitter to keep the optical axis of the imaging system aligned with the mechanical central axis of the extraction system; Adjust the horizontal position of the fiber optic light source and the beam expander so that the incident light is focused on the mechanical center after being reflected by the beam splitter. The mechanical center mark is observed through the imaging field of view of the imaging system until the mark is located at the center of the imaging image.

8. The installation method according to claim 1, characterized in that, Before automatically adjusting the sample stage position based on the imaging image to make the beam spot center of the ion beam coincide with the sample center, the method further includes: Install the lens bracket of the imaging system at the preset interface position of the extraction system, and adjust the vertical direction of the lens bracket so that the optical axis of the imaging system and the mechanical central axis of the extraction system are aligned in the vertical direction. The beam splitter is installed in the lens bracket at a preset angle, and its position is adjusted so that the center of the beam splitter coincides with the optical axis of the imaging system. Install the light source bracket at a horizontal position corresponding to the center of the beam splitter, and adjust the height and angle of the light source bracket so that its installation direction is perpendicular to the lens bracket.

9. A confocal imaging-assisted secondary ion extraction system, characterized in that, The system is applied to the installation method as described in any one of claims 1–8, wherein the secondary ion extraction system comprises: An imaging system is used to acquire beam spot imaging images of ion beam bombardment of samples and to assist in locating the position of the beam spot center relative to the sample center. The extraction system includes an extraction cavity, a reflecting spherical mirror, an extraction plate, a primary ion optical system, and a sample stage; The extraction cavity is located in the direction of the ion beam that bombards the sample. The extraction cavity has an opening near the sample side. The extraction cavity is installed with the extraction plate by a relative distance calculated based on the difference between the third distance and the first and second distances. The reflecting spherical mirrors are located on both sides of the extraction cavity to cooperate with the imaging system to determine the position of the imaging focal point and to provide spherical mirror parameter support for calculating the third distance from the imaging focal point to the sample stage. The extraction plate is positioned on the motion path of the emitted beam spot before it enters the extraction cavity. It has an opening corresponding to the beam spot and is used to determine the first distance in conjunction with the sample stage and the second distance in conjunction with the extraction cavity, providing a positional and geometric parameter reference for the calculation of the relative distance. The primary ion optical system is used to emit an ion beam to bombard the sample, the sample stage is used to adjust the sample position so that the beam spot center coincides with the sample center, and the position parameters of the sample stage are used to calculate the first distance from the sample stage to the extraction plate.

Images