A method and apparatus for three-dimensional scanning secondary ion mass spectrometry of a semiconductor sample

Abstract

The application provides a three-dimensional scanning secondary ion mass spectrometry analysis method and device for a semiconductor sample, and belongs to the technical field of secondary ion mass spectrometry analysis. The method provided by the application establishes a correlation between the ion flow intensity of a primary ion beam and the ablation speed, determines a scanning depth according to the correlation, performs multiple surface scans on a semiconductor sample according to the scanning depth, determines a resolution unit volume according to the beam spot area of the primary ion beam and the scanning depth, and performs element analysis on the semiconductor sample in the resolution unit volume. The three-dimensional scanning secondary ion mass spectrometry analysis method and device for a semiconductor sample provided by the application are used to improve the accuracy of semiconductor sample analysis.

Description

Technical Field

[0001] This application relates to the field of secondary ion mass spectrometry analysis technology, and in particular to a three-dimensional scanning secondary ion mass spectrometry analysis method and apparatus for semiconductor samples. Background Technology

[0002] Secondary ion mass spectrometry (SIMS) technology, with its high detection sensitivity, wide dynamic range, and excellent depth resolution, has become an indispensable key detection method for in-depth elemental analysis and micro-area composition analysis in the semiconductor industry. From dose monitoring in ion implantation processes to interface contamination analysis of metal interconnect structures, SIMS technology plays an irreplaceable role in semiconductor device development, process optimization, and yield improvement.

[0003] Conventional SIMS analysis methods primarily rely on primary ion beams to bombard and strip the sample surface, followed by mass separation and signal acquisition of secondary ions generated during sputtering using a mass spectrometer. In typical depth profiling mode, the primary ion beam reciprocates within a fixed micro-region of the sample surface using a raster scanning method. As sputtering time accumulates, the sample is stripped layer by layer, and the detector simultaneously records the variation curves of secondary ion signal intensity for each target element over sputtering time. Finally, by measuring the physical depth of the sputtering crater, the time axis is converted to the depth axis, obtaining the distribution information of elemental concentration with depth. In imaging analysis mode, a focused primary ion beam performs a two-dimensional scan of the sample surface to acquire a planar distribution image of specific elements within a micro-region.

[0004] However, existing secondary ion mass spectrometry (SIMS) techniques often require increasing the primary ion beam current or extending the single-point dwell time to obtain sufficient secondary ion signal intensity for detecting low-concentration impurities. This leads to an increase in the single-layer ablation depth, sacrificing longitudinal depth resolution and making it difficult to effectively screen for low-concentration impurities. Furthermore, existing 3D analysis functions mostly employ oversampling scanning modes, where the beam scan step is smaller than the beam spot size. This results in the same sample surface location being bombarded multiple times in a single scan, exacerbating non-uniform ablation of the sample surface and introducing quantitative bias due to element fractionation effects during repeated sputtering, thus reducing the accuracy and depth resolution of 3D reconstruction data. In addition, in traditional single-point or small-area analysis modes, the selection of the analysis area highly depends on the operator's prior judgment. After analysis, only the depth distribution curve of that fixed area can be obtained, resulting in low data utilization efficiency. This prevents flexible signal accumulation and statistical screening of any sub-region of interest within the sample's 3D space, limiting the further application of SIMS technology in the analysis of complex semiconductor structures. Summary of the Invention

[0005] In view of this, this application provides a three-dimensional scanning secondary ion mass spectrometry analysis method and apparatus for semiconductor samples, in order to solve the problems of insufficient sensitivity and inherent limitations of single-point analysis in existing SIMS instruments for analyzing semiconductor samples.

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

[0007] The first aspect of this application provides a three-dimensional scanning secondary ion mass spectrometry analysis method for semiconductor samples, the method comprising:

[0008] The correlation between the ion current intensity and the ablation rate of a primary ion beam is established, and the scanning depth is determined based on the correlation.

[0009] The semiconductor sample is scanned multiple times according to the scanning depth;

[0010] The volume of the resolving unit is determined based on the spot area of ​​the primary ion beam and the scanning depth.

[0011] Elemental analysis of the semiconductor sample is performed based on the resolution unit.

[0012] A second aspect of this application provides a three-dimensional scanning secondary ion mass spectrometry analysis device for semiconductor samples, the device comprising a depth calibration module, a scanning module, and an analysis module;

[0013] The depth calibration module is used to establish the correlation between the ion current intensity and the ablation rate of a primary ion beam, and to determine the scanning depth based on the correlation.

[0014] The scanning module is used to perform multiple surface scans on the semiconductor sample according to the scanning depth;

[0015] The scanning module is also used to determine the volume of the resolution unit based on the spot area of ​​the primary ion beam and the scanning depth;

[0016] The analysis module is used to perform elemental analysis on the semiconductor sample based on the resolution unit.

[0017] The three-dimensional scanning secondary ion mass spectrometry analysis method and apparatus for semiconductor samples provided in this application establishes a quantitative correlation between the primary ion beam intensity and the ablation rate in advance, and performs voxel-level elemental analysis layer by layer based on this relationship, achieving high-throughput and high-precision quantitative characterization of elemental distribution in three-dimensional space while ensuring depth resolution. Specifically, the introduction of correlation transforms the depth stripping amount from empirical estimation into a traceable parameter based on physical standards, ensuring the consistency and controllability of the depth increment in each round of surface scanning and providing an accurate longitudinal benchmark for 3D reconstruction. Multiple surface scans based on the scanning depth ensure orderly stripping of the sample along the depth direction, avoiding spatial distortion caused by accumulated depth errors. A cuboid voxel is defined as the smallest resolvable unit using the product of the beam spot area and the scanning depth, establishing a regular and uniform data grid for the 3D analysis space, ensuring that elemental signals at any location can be uniquely assigned to the corresponding voxel. Elemental analysis within voxels supports independent integration and signal accumulation for any custom 3D sub-region and facilitates automatic location of the optimal signal-to-noise ratio analysis area through voxel-level screening. This significantly improves data utilization efficiency while effectively suppressing the adverse effects of fractionation and edge effects on quantitative accuracy, effectively improving the accuracy of semiconductor sample analysis, suppressing the adverse effects of fractionation during analysis, and simultaneously improving data utilization efficiency. Attached Figure Description

[0018] Figure 1 A flowchart of Example 1 of the three-dimensional scanning secondary ion mass spectrometry analysis method for semiconductor samples provided in this application;

[0019] Figure 2 This is a schematic diagram of the structure of a two-dimensional scanning secondary ion mass spectrometry analysis device for semiconductor samples provided in this application. Detailed Implementation

[0020] 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.

[0021] 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.

[0022] 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."

[0023] The following specific embodiments are given to illustrate the technical solution of this application in detail.

[0024] Figure 1 This is a flowchart of Example 1 of the three-dimensional scanning secondary ion mass spectrometry analysis method for semiconductor samples provided in this application. Please refer to... Figure 1 The method provided in this embodiment may include:

[0025] S101. Construct the correlation between the ion current intensity of the primary ion beam and the ablation rate, and determine the scanning depth based on the correlation.

[0026] Specifically, scanning stripping is performed on standard samples, and the bombardment depth is recorded when a fixed bombardment duration is reached. Based on the bombardment depth, fixed bombardment duration, and single ion current intensity, the erosion depth coefficient corresponding to the unit ion current intensity per unit time is calculated. When analyzing semiconductor samples, the target scanning depth is preset, and the time parameters required for a single-round surface scan are deduced based on the erosion depth coefficient and real-time ion current intensity.

[0027] Furthermore, under instrument parameters identical to those used for the analysis of the sample to be tested, a primary ion beam was applied to the surface of the standard sample for scanning and ablation. The bombardment was stopped when the ablation time reached a fixed duration, and the bombardment depth obtained from the start to the stop was recorded. The average intensity of the primary ion current during this period was measured using the formula k=D / (T×I). p The erosion depth coefficient k is calculated, and the erosion depth coefficient is a quantitative expression of the correlation; where D is the preset value of erosion depth, T is the bombardment duration, and I... p The average intensity of the ion current.

[0028] Furthermore, during the formal analysis of semiconductor samples, the desired scanning depth H for each round is set, based on the real-time monitored ion current intensity I. p Given the coefficient k, calculate the total time parameter t = H / (k × Ip) required for each face scan, and use this time parameter to control the duration of a single scan.

[0029] Furthermore, the steps to establish the correlation between the ion current intensity and the ablation rate of a primary ion beam include:

[0030] (1) A single ion beam is applied to the surface of a standard sample for a fixed duration of scanning ablation to form sputtering pits;

[0031] Specifically, a standard sample with the same or similar substrate material as the semiconductor sample to be tested is selected; under instrument parameters that are completely consistent with those of the sample to be tested in subsequent analysis, a primary ion beam is introduced into the sample surface; a scanning area of ​​a preset area is delineated on the surface of the standard sample, and the primary ion beam is controlled to perform reciprocating scanning bombardment within this area for a fixed duration of T; after the bombardment is completed, the surface of the standard sample is physically peeled off, forming a sputtering pit with a flat bottom.

[0032] Furthermore, a standard sample with known composition and good homogeneity is selected. Its matrix material should be the same as or have similar sputtering yield characteristics to the semiconductor sample under test, such as both being single-crystal silicon or gallium arsenide, to ensure the calibration results are transferable at the matrix effect level. The primary ion beam parameters of the instrument are completely set to the same state as those in the subsequent formal analysis, including accelerating voltage, beam current, beam spot size, and scanning area. Any difference in parameters may lead to changes in the ablation rate, thus introducing calibration errors. After preparation, the primary ion beam is guided to a pre-defined rectangular or square area on the surface of the standard sample. The beam spot moves continuously back and forth within this area according to a preset scanning path, with the total bombardment time fixed at T. The high-energy bombardment of the primary ions gives the atoms on the sample surface enough energy to overcome the surface binding energy and be expelled, i.e., sputtering occurs. As the bombardment time accumulates, material in the scanning area is continuously removed, eventually forming a relatively flat bottom and sloped sidewalls on the sample surface, i.e., a sputtering pit.

[0033] In addition, the size of the scanning area is positively correlated with the number of scanning points. The more scanning points, the larger the scanning coverage. It is understandable that as the number of scanning points increases, the scanning range increases, which in turn leads to an increase in scanning time. Therefore, before scanning and ablating the surface of the standard sample, the optimal analysis area can be determined based on the physical quality of the beam spot and the signal intensity. By performing a pre-scan on the standard sample, the area with the most regular beam spot shape and the clearest edge formed by the single ion beam at the center of the deflection field of view with the smallest aberration is found to be distortion-free. Within this area, a clean surface interval with uniform signal intensity and no obvious fluctuations or defects is selected. At the same time, it is ensured that the lateral size of the selected area is sufficient to cover the typical characteristic structure of the semiconductor device under test and accommodate the redundant area required for in-depth analysis. Then, within this range, a set of scanning points is locked with the beam spot size as the grid unit, so that adjacent beam spots are connected at the edges to achieve successive adjacent and non-overlapping complete coverage. This achieves the optimal balance between beam spot physical quality, signal representativeness, analytical range universality, lateral resolution and single-round scanning time, serving as the fixed scanning area and scanning point parameters in all subsequent correlation calibrations and quantitative analyses.

[0034] Furthermore, the sample surface can be bombarded at a single point by using an ion beam to bombard a point on the surface of a standard sample, resulting in a sputtering crater at that point, without the need to confirm the optimal region.

[0035] (2) Measure the depth of the sputtering pit, calculate the ion current intensity per unit time based on the fixed duration and the depth, and determine the correlation based on the ion current intensity per unit time.

[0036] Specifically, the standard sample is removed from the analysis chamber and scanned along the centerline of the sputtering crater using a surface profilometer to obtain the cross-sectional profile curve of the sputtering crater. The vertical distance of the flat area at the center of the sputtering crater relative to the original sample surface is read from the profile curve and taken as the physical depth D of the sputtering crater. The average intensity I of the primary ion current monitored in real time within a fixed period is obtained. The ablation depth coefficient k is calculated according to the formula k=D / (T / N×I), which represents the material thickness that a unit ion current can ablate per unit time. The ablation depth coefficient k and its corresponding instrument parameter status are stored as a correlation for subsequent analysis of the sample to be tested. N is the number of scanning points, thus obtaining the ablation efficiency of each spot.

[0037] Furthermore, after the bombardment, the standard sample is removed from the vacuum analysis chamber and transferred to the measurement platform of the surface profilometer. The profilometer probe or optical probe scans along the diameter of the sputtering crater or a preset measurement trajectory, recording the displacement change of the probe in the vertical direction to generate a profile curve reflecting the cross-sectional morphology of the sputtering crater. Since the bombardment dose distribution of the primary ion beam in the scanning area usually exhibits a uniform distribution in the center and a gradual change at the edges, the central region at the bottom of the sputtering crater is relatively flat. From the profile curve, the vertical drop between the bottom surface of the flat area and the original sample surface is measured as the physical depth D of the sputtering crater formed by this bombardment. The primary ion current intensity data recorded by the instrument during the execution is retrieved, and the average current value I during the entire bombardment period is calculated. The depth D is divided by the ratio of the bombardment duration T to the number of scanning points to obtain the average erosion velocity v = D / T / N. Then, v is divided by the average current I to obtain the normalized erosion depth coefficient k. The ablation depth coefficient is the material thickness that can be ablated per second for every 1 nanoampere of ion current under the current instrument parameter combination. The ablation depth coefficient establishes a direct mathematical correlation between the abstract ion current intensity and the specific material ablation depth. The ablation depth coefficient, along with corresponding instrument status parameters such as accelerating voltage, beam size, and scanning area, is recorded and stored in the system calibration database. During subsequent analysis of the semiconductor sample under test, the correlation is automatically invoked, and the actual ablation depth H = k × I × t is calculated based on the real-time monitored ion current intensity and the preset single-round scan time; or, based on the preset target depth H, the required scan time t = H / (k × I) is calculated.

[0038] By applying a single ion beam to the surface of a standard sample for a fixed duration to scan and etch, forming a sputtering pit, and then measuring the physical depth of the sputtering pit, the etch depth coefficient per unit ion current intensity per unit time is calculated. This establishes a quantitative correlation between the single ion current intensity and the etch rate, realizing the transformation of the etch amount in the depth direction from empirical estimation to quantitative calibration using physical standards. This allows for the accurate calculation and pre-control of the depth increment corresponding to each scan during subsequent multi-round surface scanning of the semiconductor sample under test, based on real-time monitored ion current intensity. This provides a traceable and consistent longitudinal scale benchmark for three-dimensional voxel partitioning, effectively avoiding the three-dimensional spatial reconstruction distortion problem caused by depth accumulation error or beam fluctuation, and ensuring the quantitative accuracy and spatial resolution in the depth direction of three-dimensional element distribution analysis.

[0039] Furthermore, the steps for determining the scanning depth based on the aforementioned correlation include:

[0040] (1) Obtain the scanning time of a single round of scanning;

[0041] Specifically, the scanning range and scanning path parameters for a single-wheel surface scan are set; the scanning time required to complete one full coverage is calculated based on the scanning range area, beam spot stepping speed, or pixel dwell time; during the formal analysis, the scanning execution status is monitored in real time, and the actual scanning time is recorded for subsequent depth calculation.

[0042] Furthermore, the single-round scan time refers to the time required for the ion beam to completely cover the target area and redundant areas of the sample in one pass. Before scanning begins, the user or system sets the scan area size, beam spot size, and scan mode parameters, such as point-by-point dwell time or continuous scan rate. For point-by-point scan mode, the single-round scan time equals the total number of scan points multiplied by the dwell time per point; for continuous scan mode, it equals the total length of the scan path divided by the beam spot movement linear velocity. Using these parameters, the system can pre-calculate the theoretical scan time. It should be noted that point-by-point dwell time or continuous scan rate refers to dwell or continuity in the time dimension; in reality, there is no gap between the previous scan area and the next scan area, and they are closely connected.

[0043] Furthermore, during the actual scanning process, the system can also control the recording of the time difference between the start of the scan and the moment when the last spot is acquired, which can be used as the actual scanning time.

[0044] (2) Calculate the scanning depth based on the product of the scanning time, ion current intensity and erosion depth coefficient.

[0045] Specifically, during the single-round scanning process, the intensity of the primary ion current is acquired and recorded in real time using a Faraday cup or sample current monitoring circuit installed in the primary ion beam optical path. The ion current intensity data sequence acquired during the single-round scanning is averaged to obtain the average ion current intensity of that round of scanning. The ablation depth coefficient corresponding to the analytical conditions is retrieved from the calibration database. The average ion current intensity, the single-round scanning time, and the ablation depth coefficient are multiplied to obtain the actual scanning depth corresponding to that round of scanning.

[0046] Furthermore, during the initial ion beam bombardment of the sample, some primary ions escape as secondary electrons or secondary ions after interacting with the sample. However, the net current absorbed by the sample reflects the actual intensity of the primary ion current. By connecting a high-precision galvanometer in series between the sample stage and ground, the sample absorption current can be monitored in real time, and the primary ion current intensity can be calculated. Since the emission current from the ion source may drift slowly, it is not a constant value at different times within a single scan. Therefore, the data acquisition system samples the primary ion current intensity at fixed time intervals, obtaining a sequence of current values. The arithmetic mean of this sequence is calculated as the representative current intensity for this scan. The calibration database is accessed to retrieve the ablation depth coefficient matching the current accelerating voltage, beam spot size, and scanning area. A multiplication operation is performed to obtain the actual material thickness ablated during this scan. The material thickness will be used as a longitudinal dimension parameter, together with the transverse dimensions L and W of the beam spot, to define the depth dimension of the cuboid voxel unit generated by this scan. By calculating and recording the corresponding material thickness in each round, the true depth of each scan layer can be obtained, providing a reliable basis for the uniform division of the three-dimensional voxel mesh and the accurate spatial positioning of element signals.

[0047] Optionally, the scanning process is implemented based on a mass spectrometry imaging device, which includes a scanning module and a data acquisition module. The scanning module is used to perform three-dimensional scanning of the semiconductor sample, and the imaging micro-hole in the scanning module is square. The data acquisition module is used to collect the scanning data from the scanning module and perform elemental analysis on the semiconductor sample.

[0048] Specifically, the scanning module generates a primary ion beam spot with a specific geometry and controls its precise movement on the sample surface. In traditional secondary ion mass spectrometry instruments, the imaging microaperture is usually circular, resulting in a circular or elliptical beam spot. This leads to overlapping areas or uncovered gaps between adjacent scans, affecting depth resolution and quantitative accuracy. A square imaging microaperture is used, with clearly defined length and width boundaries. When the primary ion beam passes through this square imaging microaperture and is focused onto the sample surface by the ion optical lens group, the beam spot cross-section is a rectangle conjugate to the microaperture shape, denoted as L×W. The clear and regular boundaries of the rectangular beam spot allow the beam spots of adjacent scans to be arranged with precisely connected edges, eliminating both overlapping bombardment areas and missed scan areas. The movement of the beam spot on the sample surface is controlled by two sets of deflection electrodes: one controlling displacement along the X-direction and the other controlling displacement along the Y-direction. For successive adjacent scan modes, the displacement of each beam spot step is precisely equal to the beam spot length L or width W. In a single-round surface scan, the beam spot starts from the initial angle and moves grid by grid along the first direction. After completing one row, it steps one beam spot width along the second direction and scans the next row in reverse, repeating this process until the entire preset scanning area is covered. The scanning area consists of the target analysis area and a redundant area surrounding it. The redundant area ensures that even if redeposition occurs on the sputtering crater sidewalls or edge distortion occurs in the extraction electric field as the depth increases, the signal acquisition in the central target area remains stable. After a single round of scanning, a layer of material of uniform thickness is peeled off the sample surface, and the next round of surface scanning with the same scanning path is repeated. After multiple rounds of scanning, the sample is peeled off layer by layer, forming continuous sampling in the depth direction.

[0049] Furthermore, the data acquisition module is responsible for converting the secondary ions generated during the physical stripping process into quantifiable elemental signals. At the instant the primary ion beam bombards a voxel location on the sample surface, sample atoms are sputtered off the surface, some of which escape in ionic form, known as secondary ions. A positive or negative bias voltage is applied to the extraction electrode to draw these secondary ions into the mass spectrometer inlet. For the target element, the mass spectrometer only allows ions with a specific mass-to-charge ratio to pass through and reach the detector. The detector outputs an electrical pulse signal or analog current signal proportional to the number of ions. The data acquisition system simultaneously records two sets of information with extremely high temporal resolution: one is the signal intensity from the detector, and the other is the real-time beam spot position coordinates from the scan controller. Through timestamp alignment, each signal intensity value is precisely labeled with its spatial location, indicating which scan round, row, and column it belongs to. After multiple scan rounds, these spatially labeled signal data form a three-dimensional array, with each array element corresponding to a cuboid voxel of size L×W×H. Building upon this foundation, the data analysis software offers interactive visualization and analysis capabilities: users can rotate and section the 3D data cube to observe the spatial distribution of elements within the sample; they can also use interactive tools such as selection boxes and lasso to customize and select 3D sub-regions of arbitrary shapes and sizes, and the software automatically calculates the signal sum of all voxels within that region, enabling quantitative analysis of local areas. Furthermore, the software can perform automated feature recognition, such as identifying connected voxel sets with signal intensities several times higher than the background threshold, labeling them as impurity accumulation areas, and outputting their volume, location, and total signal quantity, providing crucial data support for semiconductor device failure analysis and process monitoring.

[0050] By obtaining the accurate scanning time of a single-round surface scan and multiplying it with the real-time monitored ion current intensity and the ablation depth coefficient obtained through pre-calibration using standard samples to calculate the scanning depth, this step transforms the ablation amount in the depth direction from relying on empirical estimation or fixed parameter settings to adaptive quantitative determination based on actual scanning dynamics and beam state. This ensures that the depth increment corresponding to each round of surface scan can truly reflect the impact of ion beam fluctuations and scanning time differences on the material ablation amount during the scanning process. This provides a longitudinal scale benchmark with real-time calibration capability for three-dimensional voxel segmentation, effectively eliminating the interlayer depth accumulation error caused by factors such as ion current drift and scanning path execution deviation. It ensures the accuracy of the longitudinal scale of the three-dimensional reconstruction space and the uniformity of voxel boundaries in the depth direction after multiple rounds of scanning are superimposed, thereby improving the accuracy and repeatability of subsequent voxel-level element signal repositioning and three-dimensional quantitative analysis.

[0051] S102. Perform multiple surface scans on the semiconductor sample according to the scanning depth.

[0052] Specifically, by adjusting the bias electrode in the primary ion optical system, the primary ion beam forms a rectangular beam spot on the sample surface; the beam spot is controlled to continuously scan along the first direction to form a strip-shaped stripping area. After completing one strip, the beam spot width is stepped along the second direction to continue scanning the next strip until the entire target area is covered; after completing a single round of complete coverage, the above scanning process is repeated until the cumulative stripping depth reaches the preset total depth.

[0053] Furthermore, in terms of scanning path control, a serpentine scanning strategy is adopted. The beam spot starts from one corner of the target region and moves continuously or quasi-continuously along a first direction, stripping a strip of width W and length equal to the side length of the region on the sample surface. After reaching the boundary, the beam spot advances a distance L along a second direction perpendicular to the first direction, and then continues scanning the next strip in the opposite direction of the first direction. This process is repeated, like a serpentine snake, until the entire target region and redundant regions are covered. This reduces the acceleration and deceleration of the beam spot at the boundary and the backsweep travel, improving scanning efficiency. After each scan stripping a layer of material of thickness H, the beam spot returns to the initial position and repeats the same serpentine scanning path on the updated sample surface. After multiple cycles, the sample is stripped layer by layer to the target total depth, and the mass spectrometer simultaneously acquires secondary ion signals at each scanning position.

[0054] Optionally, when performing surface scanning on the semiconductor sample, a redundant region is determined based on the number of scans and the total scanning depth, and the redundant region is arranged outside the analysis area of ​​the semiconductor sample.

[0055] Specifically, the total scanning depth is determined by the product of the total number of scanning rounds and the depth of a single round, or by directly obtaining a preset total scanning depth parameter. Based on the total scanning depth, combined with the incident angle of the primary ion beam and the morphology of the sputtering pit sidewall, the redeposition influence range and the edge distortion range of the extraction electric field at the edge of the sputtering pit are estimated when the total depth is reached. The larger value between the redeposition influence range and the edge distortion range of the extraction electric field is taken as the redundancy width, and a redundant region with a width equal to the redundancy width is added to the outer periphery of the target analysis area to form an expanded actual scanning area. The primary ion beam is controlled to perform multi-round surface scanning on the expanded scanning area composed of the target analysis area and the redundant region, so that the central target analysis area is always under steady-state sputtering and uniform ion extraction conditions throughout the entire depth profiling process.

[0056] Furthermore, a redundant region is set outside the target analysis area. The width R of the redundant region is dynamically or pre-estimated based on the total scanning depth. The projected width of the sidewall on the horizontal plane at the total scanning depth can be estimated based on the average tilt angle of the sputtering crater sidewall. Simultaneously, combined with known characteristics of the electric field distribution extracted by the instrument, the influence distance of edge electric field distortion is determined. The larger of the two values ​​is taken as the redundant width, ensuring that even at the maximum analysis depth, all non-ideal effects caused by sidewall redeposition and electric field distortion are confined within the redundant region, while the central target analysis area remains under ideal analytical conditions of vertical ion beam bombardment and uniform electric field extraction.

[0057] At the scanning execution level, the actual scanning range of a single ion beam is expanded by adding redundant width to each side of the original target analysis region. The scanning parameters within the redundant region are completely consistent with those of the target region, and point-by-point signal acquisition is also performed. However, the data in this redundant region is only used as an edge buffer in subsequent 3D reconstruction and quantitative analysis and is not included in the final calculation of the elemental content of the target region. Through this setting, even if the depth continues to increase during multi-round surface scanning, the signal acquisition of the target analysis region is never disturbed by edge effects, thus ensuring the spatial fidelity and quantitative accuracy of the 3D elemental distribution data.

[0058] Furthermore, the implementation of performing multiple surface scans on the semiconductor sample according to the scanning depth includes:

[0059] (1) Divide the surface area of ​​the semiconductor sample according to the beam spot area, and determine the movement path of the primary ion beam according to the divided grid array;

[0060] Specifically, the lateral dimension L and vertical dimension W of the rectangular beam spot formed by a single ion beam on the sample surface are obtained to determine the beam spot coverage area; the boundary coordinates of the area to be scanned are matched with the beam spot size, and the entire scanning area is divided into a regular grid array consisting of several rows and columns on a two-dimensional plane, with the size of each grid cell equal to the beam spot size L×W; a unique row index and column index are assigned to each grid cell to establish a grid coordinate system; according to the preset scanning strategy, the order in which the ion beam traverses all grid cells is determined, and a movement path sequence containing the center coordinates or boundary coordinates of each grid cell is generated.

[0061] Furthermore, the system reads the actual dimensions of the ion beam spot in the current instrument state, namely its length L and width W. These dimensions are determined by the imaging microaperture aperture and the magnification of the ion optics system, serving as the spatial reference for subsequent grid division. The system obtains the user-defined boundary of the target analysis region and, combined with the width of the redundant region, determines the actual area to be scanned. The length and width of this expanded region are then divided by the beam spot length L and width W, respectively, to calculate the number of rows and columns of the grid. If the region boundary is not divisible by the beam spot size, the system automatically expands the region boundary to an integer multiple of the beam spot size, ensuring complete coverage of the entire scanning area without gaps at the edges. Each grid cell corresponds to a beam spot dwell position, with a coverage area of ​​L×W. The system assigns a unique two-dimensional index to each grid cell, for example, with the lower left corner as the origin, row numbers increasing from 1 to M, and column numbers increasing from 1 to N, forming an M-row, N-column grid array. Based on this, the system generates a movement path sequence according to a preset scanning strategy. Starting from the first row and first column, the system moves sequentially along the row direction to the Nth column, completing the first row scan. Then, it steps along the column direction by a beamwidth W, entering the second row, and then moves sequentially from the Nth column back to the first column, repeating this process until all M rows and N columns of the grid have been traversed. The movement path sequence is composed of the center coordinates or boundary coordinates of each grid cell arranged in the scanning order. This movement path sequence is transmitted to the beam deflection control system to guide beam positioning during the actual scanning process.

[0062] (2) Control the primary ion beam to scan the semiconductor sample according to the moving path to complete the scanning coverage of the semiconductor sample.

[0063] Specifically, the motion path sequence is loaded into the primary ion beam deflection control unit; the deflection control unit applies corresponding voltage signals to the X-direction deflection electrode and the Y-direction deflection electrode sequentially according to the coordinate information in the motion path sequence; the primary ion beam is deflected sequentially under the action of the deflection electric field, so that the beam spot is positioned sequentially at each grid cell position specified in the motion path sequence; each time the beam spot reaches a grid cell position, it stays at that position for a preset dwell time, during which the mass spectrometry data acquisition module synchronously acquires the secondary ion signal generated at that position; when the beam spot has traversed all grid cell positions in the motion path sequence, a single-round surface scan coverage is completed, and the next round of scanning begins or the scanning process ends.

[0064] Furthermore, the movement path sequence is parsed into a series of discrete coordinate points and corresponding dwell time commands, which are loaded into the deflection controller's buffer. The deflection controller contains two independent digital-to-analog conversion channels, driving the X-direction deflection electrodes and the Y-direction deflection electrodes respectively. For each grid coordinate in the path sequence, the controller calculates the voltage increment required to deflect the beam spot from its current position to the target position and applies it to the deflection electrodes in a ramp or step manner. The primary ion beam is subjected to Lorentz force or electrostatic force in the deflection electric field, causing its direction of travel to deflect, thereby displacing the projection position of the beam spot on the sample surface accordingly. The step size of each displacement is precisely controlled as the beam spot length L or width W, so that the beam spot coverage areas of adjacent scans are arranged in a way that the edges meet and do not overlap. After the beam spot reaches the target grid position, it dwells at that position for a preset dwell time. The length of the dwell time determines the accumulation of secondary ion signals at that voxel position. During the dwell time, the primary ion beam continuously bombards the grid region, and the secondary ions generated by sputtering are extracted and analyzed by the mass spectrometer. The data acquisition module associates the detected signal intensity with the row and column index of the grid and the current scan round. After the dwell time ends, the beam spot is controlled to move to the next grid position in the path sequence. When the beam spot has traversed all M×N grid cells in sequence, the single-round surface scan is considered complete. At this point, the surface of the entire expanded scan area has been uniformly stripped of a layer of material with a thickness equal to the scanned layer. If the preset total analytical depth has not been reached, the next round of the same path sequence will be repeated until the cumulative stripping depth meets the analytical requirements. Through the above grid division and path control mechanism, the primary ion beam completes the point-by-point scanning coverage of the entire sample surface in a regular and orderly manner, providing original signal data with precise spatial location correspondence for subsequent three-dimensional voxel data reconstruction.

[0065] By dividing the semiconductor sample surface into two-dimensional regular grids using the area of ​​a single ion beam spot as the smallest grid unit, and planning the successive movement path of the beam spot based on the divided grid array, the beam spot is controlled to be positioned and scanned sequentially along the path in an edge-connected and non-overlapping manner. This step achieves complete, uniform, and orderly coverage of the test area and its redundant areas, ensuring that any point in the target area is bombarded by the ion beam only once during a single-round surface scan. This fundamentally eliminates the problems of repeated bombardment and non-uniform ablation caused by beam spot overlap in traditional oversampling modes, ensuring the uniformity of the ablation thickness of each material layer and the stability of the depth direction resolution. At the same time, it provides a spatially accurate and clearly defined two-dimensional coordinate reference for accurately assigning the secondary ion signal of each scanning position to the corresponding cuboid voxel unit, thus laying a regular and distortion-free spatial grid foundation for the reconstruction of three-dimensional element distribution data.

[0066] Optionally, each surface scan is performed using a successive adjacent scan method. The scanning positions of the beam spots of two adjacent ion beams are arranged in a way that the edges are connected and do not overlap. During each surface scan, any point on the surface of the semiconductor sample is bombarded by an ion beam only once.

[0067] Each round of surface scanning is performed by a successive adjacent scanning method, so that the scanning positions of two adjacent rectangular beam spots are arranged in a way that the edges are precisely connected and do not overlap. This ensures that any point on the sample surface is bombarded by the ion beam only once during a single round of scanning. This fundamentally eliminates the problem of the same sample position being bombarded repeatedly due to partial overlap of beam spots in the traditional oversampling scanning mode from the scanning mechanism level. Its technical advantages are as follows: First, it avoids local non-uniform ablation caused by repeated bombardment, ensuring that the thickness of the material stripped in the target area in each scan is highly consistent, thus guaranteeing that the resolution in the depth direction is not degraded due to the scanning method. Second, it effectively suppresses the elemental fractionation effect exacerbated by multiple sputterings at the same location and the accumulation of matrix damage induced by ion implantation, making the acquired secondary ion signals more realistically reflect the original composition information of the sample rather than the cumulative effect of bombardment history. At the same time, the non-overlapping beam spot coverage method makes each cuboid voxel unit have clear boundaries and is independent of each other in the lateral space, providing a precise data grid without spatial overlap for the subsequent accurate placement of mass spectrometry signals into the corresponding voxels and the execution of regional integration operations, thereby improving the quantitative accuracy and spatial fidelity of three-dimensional elemental distribution reconstruction.

[0068] S103. Determine the volume of the resolution unit based on the spot area of ​​the primary ion beam and the scanning depth.

[0069] Specifically, the effective length L of the beam spot formed by the ion beam on the sample surface along the first direction and the effective width W along the second direction are obtained; the single-round scanning depth H determined by the correlation relationship and actually executed is obtained; with L as one side length of the bottom surface, the step amount along the second direction in the single-round scanning as the other side length of the bottom surface, and H as the height, a cuboid or parallelepiped voxel is defined as the smallest resolution unit.

[0070] Furthermore, the spatial resolution variation caused by the continuous movement of the beam spot during scanning was considered. In serpentine scanning mode, the beam spot moves continuously along the first direction, and the effective signal integration length in the first direction is the beam spot length L; while along the second direction, the beam spot moves in a discrete step manner, with the step size equal to the beam spot width W. Therefore, the actual coverage area of ​​a cell of the two-dimensional grid on the sample surface is an L×W rectangle. The product of the beam spot area and the scanning depth is used as the volume of the resolution cell, and the resolution cell is used as the smallest resolution cell to analyze the semiconductor sample.

[0071] S104. Perform elemental analysis on the semiconductor sample based on the resolution unit.

[0072] Specifically, after multiple rounds of surface scanning, a three-dimensional data array containing the element content information of all resolving units is constructed; the element signal gradient value between each resolving unit and its spatially neighboring resolving units is calculated; based on a preset gradient threshold, the boundaries of resolving units where the element content changes abruptly in space are identified and marked, and the region of interest with abnormal element distribution is defined; the element signals of all resolving units in the region of interest are integrated, and the cumulative element content and spatial boundary coordinates of the region of interest are output.

[0073] Furthermore, after data acquisition, the mass spectrometry signals from each scan, each strip, and each time segment are assigned to their corresponding resolution cells, forming a regular three-dimensional data array. An automatic boundary identification algorithm is used to discover regions of interest. For each resolution cell in the three-dimensional array, the difference in element signal intensity between it and its six adjacent resolution cells (up, down, left, right, front, and back) is calculated, and the gradient magnitude is determined. When the gradient magnitude of a resolution cell and its neighboring resolution cells exceeds a preset threshold, that resolution cell is marked as a boundary candidate voxel. Through connected component analysis, all boundary candidate resolution cells are connected into a closed surface. The set of internal resolution cells enclosed by this surface constitutes a region with an abnormal element distribution, such as an impurity enrichment region, a diffusion front, or an interface segregation layer. The spatial boundary coordinates of this region are extracted, and the element signal intensity of all resolution cells within the region is integrated to obtain the total number of elements in the abnormal region.

[0074] Furthermore, the steps for performing elemental analysis on the semiconductor sample based on the resolution unit include:

[0075] (1) Determine the analysis region based on the resolution unit, determine the step window, and select multiple candidate analysis regions within the analysis region based on the step window;

[0076] Specifically, after completing multiple rounds of surface scanning and constructing a three-dimensional voxel array, the boundary parameters of the analysis region specified by the user or preset by the system are obtained. The analysis region is composed of multiple cuboid units of size L×W×H arranged continuously in three-dimensional space. The size parameters of the stepping window are set. The size of the stepping window is expressed in terms of the number of resolving units contained in each of the three dimensions, with the size of the stepping window being less than or equal to the size of the analysis region. The stepping window is set with a step size in each of the three dimensions, expressed as an integer multiple of the resolving units. The stepping window is placed at the starting corner of the analysis region, and all resolving units within the current window coverage area are recorded as the first candidate analysis region. The stepping window is moved sequentially in the three dimensions according to the preset step size. Each time it moves, the set of resolving units within the window coverage area is recorded as a new candidate analysis region, until the stepping window traverses the entire spatial range of the analysis region, obtaining a candidate region set composed of multiple candidate analysis regions.

[0077] Furthermore, after the 3D array is constructed, the entire analyzed 3D space is composed of several rows, columns, and layers of resolution cells arranged in a regular pattern. Users can specify an analysis region of interest within this 3D space by selecting a region through an interactive interface or by inputting coordinate parameters. This region is a collection of multiple resolution cells and receives the size setting of the step window. The step window is essentially a sliding sub-region template in 3D space, and its size is also measured in voxels. For example, if it contains m voxels in the X direction, n voxels in the Y direction, and p voxels in the Z direction, then the physical size of the step window is (m×L)×(n×W)×(p×H). The size of the step window determines the size of each candidate analysis region. The step size determines the degree of spatial overlap or spacing between candidate regions. The step size can be set to be equal to the step window size to achieve non-overlapping traversal, or it can be set to be smaller than the window size to achieve overlapping dense sampling. The step window is initially placed at a preset corner point of the analysis region, such as the corner point with the smallest 3D spatial coordinates, so that one vertex of the window coincides with the corresponding vertex of the analysis region. The initial window contains all the resolvable cells, forming the first candidate analysis region. The spatial indices of each resolvable cell within this region are recorded. The stepping window moves one step distance at a time, following either the X-direction, then the Y-direction, and finally the Z-direction, or a preset priority order. After each move, the set of resolvable cells covered by the window at the new position is recorded as a new candidate analysis region. The traversal process ends when the window moves to the other boundary of the analysis region and cannot move further without exceeding the boundary. At this point, the system obtains a set containing several candidate analysis regions, each a subset of the original analysis region and composed of several complete resolvable cells.

[0078] (2) Integrate the element content of each candidate analysis region to obtain the sum of element signal intensity of each candidate analysis region;

[0079] Specifically, the resolution cell index list of each candidate analysis region is read sequentially from the candidate region set; based on the resolution index list, the element signal intensity value carried by the corresponding resolution cell is extracted from the three-dimensional data array; the extracted signal intensity values ​​are summed to obtain the sum of element signal intensities of the candidate analysis region; the calculated sum of element signal intensities is associated with and stored with the spatial boundary coordinates of the candidate analysis region to form a candidate region evaluation data record.

[0080] Furthermore, the total signal intensity of elements within a candidate analysis region is equal to the sum of the signal intensity values ​​of all voxels within that region. By traversing the set of candidate regions, for each candidate analysis region, the index positions of all its resolved cells in the three-dimensional array are obtained. The data array is then directly accessed through these indices, and the signal intensity value of each resolved cell is read. This represents the elemental signal intensity within that small volume after mass spectrometry detection and preprocessing such as baseline correction and sensitivity factor conversion. All extracted signal intensity values ​​are summed one by one to obtain the total elemental signal intensity of the candidate analysis region. The total elemental signal intensity reflects the relative or absolute total amount of the target element within the three-dimensional space of the sample corresponding to the candidate region.

[0081] Furthermore, the sum of the element signal intensity and the spatial range information of the candidate analysis region, such as the index of the start and end voxels of the region in the X, Y, and Z directions or the actual physical coordinates, are recorded together to form a complete candidate region evaluation record. After all candidate analysis regions have completed the above integration operation, a set containing the spatial location, coverage area and total signal of each candidate region is obtained.

[0082] (3) Select the target analysis region from multiple candidate analysis regions based on the sum of the element signal intensity.

[0083] Specifically, based on preset screening criteria, the sum of element signal intensities of each candidate analysis region is compared and sorted; the screening criteria include at least one of the following: the maximum value of the sum of signal intensities, the maximum value of the ratio of the sum of signal intensities to the number of voxels in the region, the region where the sum of signal intensities exceeds a preset threshold, and the region where the sum of signal intensities is a local maximum in the neighborhood; one or more target analysis regions that meet the criteria are determined from the set of candidate regions according to the screening criteria; the spatial boundary coordinates of the target analysis regions and their corresponding sum of element signal intensities are output as the analysis result.

[0084] Furthermore, the screening logic can be preset according to actual analytical needs. If the analytical objective is to find the location with the highest impurity enrichment in the sample, the screening condition can be set to select the candidate region with the largest sum of elemental signal intensities. If a fair comparison is required between candidate regions of different sizes, the average signal intensity per voxel can be calculated, i.e., the sum of signal intensities divided by the total number of voxels in the region, and the region with the largest ratio can be selected. If the analytical objective is to screen for contaminated regions exceeding a certain danger threshold, an absolute threshold can be set to screen all candidate regions with a sum of signal intensities greater than that threshold. If it is necessary to locate the central peak position of the impurity distribution, a neighborhood comparison algorithm can be used to identify candidate regions where the sum of signal intensities constitutes a local maximum within its spatial neighborhood. Based on the selected screening conditions, the candidate region evaluation data records are traversed, and corresponding numerical comparison, threshold judgment, or local extremum search algorithms are executed. Candidate analysis regions that meet the conditions are marked as target analysis regions. If multiple regions meet the conditions, they can all be output and sorted by signal intensity; if only one optimal region is needed, the region with the highest sorted value is output.

[0085] By setting a stepping window within a three-dimensional analysis region composed of multiple cuboid voxel units and sliding it along each dimension with a preset step size, multiple candidate analysis sub-regions covering different spatial locations are automatically generated. Then, the element signal intensity carried by all voxels in each candidate region is integrated and accumulated to obtain the total element signal of each region. Finally, the target analysis region is determined from the candidate set according to preset screening conditions. This method transforms the traditional single-point or fixed region selection mode that relies on the operator's subjective experience into an automated selection process based on data-driven and quantitative index comparison. On the one hand, the continuous sampling of the stepping window in space ensures that potential impurity-rich areas or abnormal composition areas within the analysis region are covered without omission. On the other hand, the evaluation mechanism based on voxel-level signal integration fully accumulates weak signals within a small volume, effectively improving the signal-to-noise ratio and statistical significance of low-impurity areas. Finally, the target criterion region obtained through objective screening not only has the best signal characterization ability, but also significantly suppresses the influence of human selection bias on the analysis results. While improving the efficiency and repeatability of three-dimensional element distribution analysis, it also ensures the accuracy of analysis conclusions and spatial positioning precision.

[0086] Furthermore, in addition to the methods described above, the steps for performing elemental analysis on the semiconductor sample based on the resolution unit may also include:

[0087] (1) Determine the analysis region based on the resolution unit, determine the preset region within the analysis region, and determine multiple candidate analysis regions within the preset region based on the beam spot area;

[0088] Specifically, a three-dimensional voxel array is acquired after multiple rounds of surface scanning. This voxel array is composed of regularly arranged cuboid voxel units with dimensions of L×W×H, and each voxel unit carries the element signal intensity value at that spatial location. Within the spatial range of the three-dimensional voxel array, an analysis region consisting of multiple continuous voxel units is defined according to preset spatial boundary parameters. The number of voxels in this analysis region is an integer in each of the three dimensions. Within the analysis region, a preset region is further selected. The spatial range of this preset region is defined by the start index and end index along the coordinate direction of the voxel array, and the dimensions of this preset region in the two horizontal dimensions are integer multiples of the length L and width W of the rectangular beam spot. The preset region is divided into several sub-regions on the horizontal plane according to the beam spot area L×W. Each sub-region corresponds to a cuboid space with a base area of ​​L×W and a vertical depth equal to the height of the preset region. Each of these cuboid spaces serves as a candidate analysis region. The index range of all voxel units contained in each candidate analysis region is recorded to form a list of candidate analysis regions.

[0089] Furthermore, after the multi-round surface scanning is completed, the acquired secondary ion signals are grouped into corresponding cuboid voxel units (i.e., resolution units) according to the scanning round and beam spot grid position, forming a voxel array uniformly sampled in three spatial dimensions. Each element in the voxel array is an independent signal intensity value, and its physical correspondence is a tiny volume of size L×W×H. Based on this voxel array, an analysis region can be delineated in three-dimensional space. The analysis region is delineated by specifying start and end indices along the three coordinate axes of the voxel array. The continuous set of voxels defined by the start and end indices constitutes the analysis region. The analysis region contains integer voxel units, and its physical size is the product of the number of voxels contained and the size of a single voxel.

[0090] Further define the preset region within the analysis region. The preset region is a subset of the analysis region, and its spatial range can be selected according to the specific needs of the analysis task, such as focusing on specific structures within a certain depth range or a certain lateral coordinate range. The size of the preset region in the lateral plane is set to an integer multiple of the beam spot length L and the width W. This setting ensures that the lateral span of the preset region is exactly divisible by the beam spot area.

[0091] Furthermore, the preset region is divided into two dimensions: a horizontal first dimension with a length L and a horizontal second dimension with a width W. This generates several adjacent and non-overlapping rectangular cylindrical spaces. The base dimension of each rectangular cylindrical space is L×W, and its height is equal to the vertical depth of the preset region. Each rectangular cylindrical space contains several vertically stacked voxel units, which together constitute a candidate analysis region. Since the horizontal dimensions of the preset region are integer multiples of L and W, the divided candidate analysis regions completely cover the preset region without leaving any boundary gaps. The spatial extent of each candidate analysis region is uniquely determined by its voxel start and end indices along the three dimensions. The index ranges of all candidate analysis regions are recorded in a list for subsequent integration calculations.

[0092] (2) Extract the element content information of each candidate analysis region, perform an integral operation on the element content information of each candidate analysis region, and obtain the sum of element signal intensity in the preset region.

[0093] Specifically, the voxel start and end indices of each candidate analysis region are read sequentially from the candidate analysis region list; the three-dimensional voxel array is accessed according to the voxel start and end indices, and the element signal intensity values ​​stored by each voxel unit within the index range are read; the read element signal intensity values ​​are summed to obtain the total signal intensity of the region corresponding to the candidate analysis region; the total signal intensity of each candidate analysis region is further summed, or the voxel signals covered by all candidate analysis regions within the preset region are summed at once to obtain the total element signal intensity of the entire preset region.

[0094] Furthermore, the elemental content information stored in each voxel unit of the voxel array is represented by the signal intensity value of that voxel location after mass spectrometry detection and quantization, reflecting the secondary ion yield of the target element when bombarding that tiny volume with a single ion beam. When extracting the elemental content information of the candidate analysis region, the row, column, and layer ranges spanned by the rectangular columnar space in the three-dimensional array are determined based on the voxel index range recorded in the candidate analysis region. Each voxel coordinate within this range is traversed, and the corresponding signal intensity value is read from the voxel array. The read values ​​are then collected into a signal dataset for the candidate analysis region. Performing an integral operation on the elemental content information involves algebraically summing all values ​​in the signal dataset. Since all voxels have equal volumes, the total signal intensity is proportional to the total number of atoms or the total ion yield of the target element within the candidate analysis region. The summation operation traverses all voxels contained within the candidate analysis region without omission or duplication.

[0095] Furthermore, after obtaining the sum of signal intensities for each candidate analysis region, the summation results for all candidate analysis regions are summed again to obtain the sum of elemental signal intensities for all voxels within the preset region. Since the candidate analysis regions do not overlap and together constitute a complete division of the preset region, this summation value is equivalent to the result of directly performing a global integral over the preset region.

[0096] The above integration process performs grouped summation on the transverse plane using the beam spot area as the basic integration unit, ensuring that the granularity of the integration operation remains consistent with the physical sampling unit during a single ion beam scan. Each candidate analysis region corresponds to the longitudinal extension of the transverse range covered by the beam spot in a single scan across multiple scan depths. Therefore, this integration method can faithfully reflect the cumulative characteristics of the three-dimensional elemental distribution with the beam spot as the transverse sampling unit.

[0097] By dividing a preset region laterally within a three-dimensional analysis space composed of cuboid voxel units according to the beam spot area L×W to generate several rectangular columnar candidate analysis regions that precisely correspond to the physical sampling units of a primary ion beam, and then performing integration and accumulation on all vertically stacked voxel signals within each candidate region to obtain the sum of element signal intensities for the preset region, the entire spatial alignment of three-dimensional element distribution data from the sampling source to the integration calculation is achieved. On the one hand, the lateral division of the candidate analysis region uses the beam spot area as the smallest unit, ensuring that the lateral granularity of the integration operation is completely consistent with the bombardment unit of the primary ion beam during surface scanning, avoiding signal attribution deviations introduced by misalignment between the beam spot coverage and the integration unit. On the other hand, the vertical accumulation of all voxel signals arranged along the depth direction within each candidate region can fully gather local signals at the lateral beam spot scale while retaining depth accumulation information, effectively improving the statistical detection capability of low-concentration impurities. Overall, this method not only ensures the completeness and coverage of the total element amount calculation within the preset region, but also enhances the accuracy and spatial correspondence of the quantitative results through the one-to-one correspondence between the physical sampling units and the calculation units.

[0098] The three-dimensional scanning secondary ion mass spectrometry analysis method for semiconductor samples provided in this embodiment establishes a quantitative correlation between the primary ion beam intensity and the ablation rate beforehand, and determines the scanning depth layer by layer accordingly. It defines a cuboid voxel, composed of the beam spot area and the single-layer ablation depth, as the smallest resolution unit, and then performs voxel-level elemental analysis. This achieves high-throughput quantitative characterization of the three-dimensional elemental distribution of semiconductor samples while ensuring depth resolution. The introduction of the correlation transforms the depth ablation amount from empirical estimation to a traceable parameter based on physical standards, ensuring the consistency and controllability of the depth increment in each round of surface scanning, and providing an accurate longitudinal benchmark for three-dimensional reconstruction. Multiple surface scans are performed based on the scanning depth to allow the sample to move along... Orderly stripping along the depth direction avoids spatial distortion caused by accumulated depth errors; a cuboid voxel is defined as the smallest resolving unit by multiplying the beam spot area and scanning depth, establishing a regular and uniform data grid for the three-dimensional analysis space, so that element signals at any position can be uniquely assigned to the corresponding voxel; elemental analysis is performed within the voxel, which not only supports independent integration and signal accumulation for any custom three-dimensional sub-region, but also facilitates automatic location of the analysis area with the optimal signal-to-noise ratio through voxel-level screening, thereby significantly improving data utilization efficiency while effectively suppressing the adverse effects of fractionation and edge effects on quantitative accuracy. Overall, it realizes high-precision screening of low-content impurities in semiconductor samples and visualization analysis of three-dimensional component distribution.

[0099] Corresponding to the aforementioned embodiment of a three-dimensional scanning secondary ion mass spectrometry analysis method for semiconductor samples, this application also provides an embodiment of a three-dimensional scanning secondary ion mass spectrometry analysis device for semiconductor samples.

[0100] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the three-dimensional scanning secondary ion mass spectrometry analysis device for semiconductor samples provided in this application. Please refer to... Figure 2 The device provided in this embodiment includes a depth calibration module 210, a scanning module 220, and an analysis module 230;

[0101] The depth calibration module 210 is used to establish the correlation between the ion current intensity and the ablation rate of a primary ion beam, and to determine the scanning depth based on the correlation.

[0102] The scanning module 220 is used to perform multiple surface scans on the semiconductor sample according to the scanning depth;

[0103] The scanning module 220 is also used to determine the volume of the resolution unit based on the spot area of ​​the primary ion beam and the scanning depth.

[0104] The analysis module 230 is used to perform elemental analysis on the semiconductor sample based on the resolution unit.

[0105] The apparatus of this embodiment can be used to perform... Figure 1 The steps of the method embodiment shown are similar in principle and process, and will not be repeated here.

[0106] The specific implementation process of the functions and roles of each unit in the above device can be found in the implementation process of the corresponding steps in the above method, and will not be repeated here.

[0107] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0108] 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 three-dimensional scanning secondary ion mass spectrometry method for semiconductor samples, characterized in that, The method includes: The correlation between the ion current intensity and the ablation rate of a primary ion beam is established, and the scanning depth is determined based on the correlation. The semiconductor sample is scanned multiple times according to the scanning depth; Specifically, the analysis region is determined based on the resolution unit, a stepping window is determined, and multiple candidate analysis regions are selected within the analysis region based on the stepping window; The element content of each candidate analysis region is integrated to obtain the sum of element signal intensities for each candidate analysis region. The target analysis region is selected from multiple candidate analysis regions based on the sum of element signal intensities. Alternatively, an analysis region may be determined based on the resolution unit, a preset region may be determined within the analysis region, and multiple candidate analysis regions may be determined within the preset region based on the beam spot area; Extract the element content information of each candidate analysis region, perform an integral operation on the element content information of each candidate analysis region, and obtain the sum of element signal intensity within the preset region; The volume of the resolution unit is determined based on the spot area of ​​the primary ion beam and the scanning depth; the effective length of the spot formed by the primary ion beam on the sample surface along the first direction and the effective width along the second direction are obtained; the single-round scanning depth determined by the correlation relationship and actually executed is obtained; with the effective length as one side of the bottom surface, the step amount along the second direction in the single-round scanning as the other side of the bottom surface, and the single-round scanning depth as the height, an oblique cuboid or parallelepiped voxel is defined as the smallest resolution unit; Elemental analysis of the semiconductor sample is performed based on the resolution unit; The surface area of ​​the semiconductor sample is divided according to the beam spot area, and the movement path of the primary ion beam is determined according to the divided grid array. The primary ion beam is controlled to scan the semiconductor sample according to the moving path to complete the scanning coverage of the semiconductor sample; each surface scan is performed in a successive adjacent scanning mode, and the scanning positions of the beam spots of two adjacent primary ion beams are arranged in a way that the edges are connected and do not overlap. During each surface scan, any point on the surface of the semiconductor sample is bombarded only once by the ion beam.

2. The method according to claim 1, characterized in that, The relationship between the ion current intensity and the ablation rate of the primary ion beam includes: A single ion beam is applied to the surface of a standard sample for a fixed duration of scanning ablation, forming sputtering pits. The depth of the sputtering pit is measured, and the ion current intensity per unit time is calculated based on the fixed duration and the depth. The correlation is determined based on the ion current intensity per unit time.

3. The method according to claim 2, characterized in that, Determining the scanning depth based on the correlation includes: Obtain the scan time for a single round of scanning; The scanning depth is calculated based on the product of the scanning time, ion current intensity, and ablation depth coefficient.

4. The method according to claim 1, characterized in that, The scanning process is implemented based on a mass spectrometry imaging device, which includes a scanning module and a data acquisition module. The scanning module is used to perform three-dimensional scanning of the semiconductor sample. The imaging micro-hole in the scanning module is square. The data acquisition module is used to collect the scanning data from the scanning module and perform elemental analysis on the semiconductor sample.

5. The method according to claim 1, characterized in that, The method further includes: When performing surface scanning on the semiconductor sample, redundant regions are determined based on the number of scans and the total scanning depth, and the redundant regions are arranged outside the analysis area of ​​the semiconductor sample.

6. A three-dimensional scanning secondary ion mass spectrometry analysis device for semiconductor samples, characterized in that, The device includes a depth calibration module, a scanning module, and an analysis module; The depth calibration module is used to establish the correlation between the ion current intensity and the ablation rate of a primary ion beam, and to determine the scanning depth based on the correlation. The scanning module is used to perform multiple surface scans on the semiconductor sample according to the scanning depth; wherein, the analysis region is determined according to the resolution unit, a stepping window is determined, and multiple candidate analysis regions are selected within the analysis region based on the stepping window; The element content of each candidate analysis region is integrated to obtain the sum of element signal intensities for each candidate analysis region. The target analysis region is selected from multiple candidate analysis regions based on the sum of element signal intensities. Alternatively, an analysis region may be determined based on the resolution unit, a preset region may be determined within the analysis region, and multiple candidate analysis regions may be determined within the preset region based on the beam spot area; Extract the element content information of each candidate analysis region, perform an integral operation on the element content information of each candidate analysis region, and obtain the sum of element signal intensity within the preset region; The scanning module is further configured to determine the volume of the resolution unit based on the spot area of ​​the primary ion beam and the scanning depth; obtain the effective length of the spot formed by the primary ion beam on the sample surface along the first direction and the effective width along the second direction; obtain the single-round scanning depth determined by the correlation relationship and actually executed; and define an oblique cuboid or parallelepiped voxel as the minimum resolution unit, with the effective length as one side of the bottom surface, the step amount along the second direction in the single-round scanning as the other side of the bottom surface, and the single-round scanning depth as the height. The analysis module is used to perform elemental analysis on the semiconductor sample based on the resolution unit; The surface area of ​​the semiconductor sample is divided according to the beam spot area, and the movement path of the primary ion beam is determined according to the divided grid array. The primary ion beam is controlled to scan the semiconductor sample according to the moving path to complete the scanning coverage of the semiconductor sample; each surface scan is performed in a successive adjacent scanning mode, and the scanning positions of the beam spots of two adjacent primary ion beams are arranged in a way that the edges are connected and do not overlap. During each surface scan, any point on the surface of the semiconductor sample is bombarded only once by the ion beam.

Images