Ellipsometer-based film thickness detection method and system

Abstract

The present application relates to the field of thickness measurement, and particularly relates to a film thickness detection method and system based on an ellipsometer. The method comprises the following steps: obtaining initial point reflection data; determining an initial point clustering cluster according to the initial point reflection data; determining an ellipsometer detection point clustering cluster according to the initial point clustering cluster; determining a spin distribution quantity according to the ellipsometer detection point clustering cluster; when the spin distribution quantity meets a preset spin distribution quantity threshold, determining a center point position according to the ellipsometer detection point clustering cluster, and determining a target detection point position according to the center point position; when the spin distribution quantity does not meet the preset spin distribution quantity threshold, determining a target perovskite film as a damaged perovskite film; obtaining reflection data of the target detection point position, and evaluating uniformity of the target perovskite film according to the reflection data of the target detection point position. The present application can greatly eliminate ellipsometer detection errors caused by surface structure problems of the perovskite film.

Description

Technical Field

[0001] This invention relates to the field of thickness measurement, and specifically to a film thickness detection method and system based on an ellipsometer. Background Technology

[0002] An ellipsometer is an optical instrument used to measure the properties of thin films on material surfaces, particularly to determine optical characteristics such as thickness, refractive index, and extinction coefficient (absorption coefficient). It is widely used in semiconductors, optical coatings, thin film technology, and materials science. The basic principle of an ellipsometer is to obtain the optical properties of a material by measuring the change in polarization state of incident light after reflection from the surface being measured. When light interacts with a material surface, phenomena such as reflection and refraction occur, especially changes in polarization state. The ellipsometer obtains the optical properties of the surface thin film by analyzing this polarization change (usually manifested as ellipsoidal polarization). The light source of an ellipsometer is typically linearly polarized light. When light shines on the sample surface, part of the light is reflected back to the ellipsometer. By measuring the polarization state of the reflected light, the ellipsometer can capture the phase and polarization direction changes that occur during the reflection process. Using these polarization changes, the ellipsometer calculates the optical constants of the material (such as refractive index and extinction coefficient) and the thickness of the thin film.

[0003] Perovskite thin films can be formed using methods such as solution deposition, evaporation, and spin coating. Different methods can affect the crystallization behavior of the film. The thickness of the perovskite thin film is measured by polarization phase acquisition analysis using an ellipsometer. In this process, spin coating is the most common method, but the uniformity of the solution, the rotation speed, and the solvent evaporation rate all affect the uniformity of the film. Furthermore, the crystallization rate varies; the crystallization rate of perovskite materials typically exhibits a gradient within the film layer. This leads to inconsistent crystallinity at different locations, thus affecting optical properties and film thickness distribution.

[0004] Therefore, when analyzing the thickness of perovskite thin films using an ellipsometer, the non-uniformity of the film thickness leads to unrepresentative results in a single region, failing to achieve complete and accurate measurement. Furthermore, when using multi-point integrated detection to compensate for film non-uniformity, improper arrangement of key detection points can result in random thickness values, failing to encompass the entire film surface. In other words, the results of multi-point fusion detection cannot reflect the specific morphology of the film, thus failing to achieve accurate analytical results. Summary of the Invention

[0005] This invention provides a film thickness detection method and system based on an ellipsometer to solve existing problems.

[0006] The film thickness detection method based on an ellipsometer of the present invention adopts the following technical solution:

[0007] One embodiment of the present invention provides a film thickness detection method based on an ellipsometer, the method comprising the following steps:

[0008] Acquire the initial point reflection data of the initial point set on the target perovskite film;

[0009] Based on the reflectance data of the initial points, determine the initial point clusters;

[0010] Based on the initial point clusters, determine the ellipsometer detection point clusters;

[0011] Based on the clustering of ellipsometer detection points, the spin coating distribution amount is determined. When the spin coating distribution amount meets the preset rotational distribution amount threshold, the center point is determined based on the clustering of ellipsometer detection points, and the target detection point is determined based on the center point. When the spin coating distribution amount does not meet the preset rotational distribution amount threshold, the target perovskite film is determined as a damaged perovskite film.

[0012] Acquire reflectance data at target detection points and evaluate the uniformity of the target perovskite film based on the reflectance data at the target detection points.

[0013] Optionally, based on the reflectance data of the initial points, the initial point clusters are determined, specifically including:

[0014] Calculate the similarity value between the first initial point and the second initial point based on the reflectance data of the initial point.

[0015] When the similarity value is within the preset similarity threshold range, the first initial point and the second initial point are determined to be in the same cluster, and the cluster in which the first initial point and the second initial point are located is determined as the initial point cluster.

[0016] Here, the first initial point and the second initial point are any different initial points among the initial points.

[0017] Optionally, the initial point reflection data includes initial amplitude data and initial phase data. Based on the initial point reflection data, the similarity value between the first initial point and the second initial point is calculated, specifically including:

[0018] Calculate the Pearson correlation coefficient between the first initial point and the second initial point to obtain the initial point correlation between the first initial point and the second initial point;

[0019] Calculate the reciprocal of the difference between the initial phase data of the first initial point and the second initial point to obtain the phase correlation;

[0020] Calculate the product of the initial point correlation and the phase correlation and normalize it to obtain the similarity value.

[0021] Optionally, based on the initial point cluster, the ellipsometer detection point cluster is determined, specifically including:

[0022] Determine the initial point of maximum thickness, and based on the initial points in each initial point cluster, determine the reflectivity of each initial point cluster;

[0023] When the reflectivity of the j-th initial point cluster meets the preset reflectivity threshold, the j-th initial point cluster is determined as the ellipsometer detection point cluster.

[0024] Optionally, based on the initial points in each initial point cluster, the reflectivity of each initial point cluster is determined, specifically including:

[0025] Calculate the mean similarity of initial points in the cluster with the j-th initial point;

[0026] Calculate the average distance between initial points in the j-th initial point cluster and the initial point with the largest thickness.

[0027] The reflectivity correlation of the j-th initial point cluster is obtained by multiplying the mean initial point similarity of the j-th initial point cluster with the reciprocal of the mean initial point similarity of the j-th initial point cluster and then normalizing the result.

[0028] Optionally, the spin coating distribution is determined based on the clustering of ellipsometer detection points, specifically including:

[0029] Obtain the membrane thickness detection values ​​of all initial points in the cluster of ellipsometer detection points, and calculate the average membrane thickness of each detection point in each cluster of ellipsometer detection points.

[0030] Obtain the distances between all initial points in the ellipsometer detection point cluster and the initial point with the maximum thickness, and calculate the mean detection point distance for each ellipsometer detection point cluster.

[0031] The spin coating distribution is calculated based on the average film thickness of each cluster of ellipsometer detection points and the average distance between each cluster of ellipsometer detection points.

[0032] Optionally, the spin coating distribution is calculated based on the average film thickness of each ellipsometer detection point cluster and the average distance between each ellipsometer detection point cluster, specifically including:

[0033] Calculate the difference between the average film thickness of the cluster at the (k+1)th ellipsometer detection point and the average film thickness of the cluster at the kth ellipsometer detection point, and take the absolute value of the difference to obtain the thickness difference of the nth adjacent cluster.

[0034] Calculate the difference between the mean distance between the clusters of the (k+1)th ellipsometer detection points and the mean distance between the clusters of the kth ellipsometer detection points, and take the absolute value of the difference to obtain the distance difference between the nth adjacent clusters.

[0035] Calculate the ratio of the distance difference between the nth and nth adjacent clusters to obtain the ratio of the nth difference;

[0036] Calculate the difference between the nth difference ratio and the preset empirical coefficient to obtain the nth theoretical spin coating distribution.

[0037] Calculate the sum and average of N theoretical spin coating distributions to obtain the average theoretical spin coating distribution.

[0038] The spin coating distribution is obtained by adding one to the mean of the theoretical spin coating distribution and then taking the reciprocal.

[0039] Optionally, the film thickness detection values ​​of all initial points in the ellipsometer detection point cluster are obtained, and the average film thickness of each detection point in the ellipsometer detection point cluster is calculated, specifically including:

[0040] The average film thickness of the initial points in the cluster of the kth ellipsometer detection points is obtained by summing the film thickness values ​​of the initial points in the cluster of the kth ellipsometer detection points.

[0041] Optionally, the distances between all initial points in each ellipsometer detection point cluster and the initial point with the maximum thickness are obtained, and the mean distance of each detection point in each ellipsometer detection point cluster is calculated, specifically including:

[0042] The average distance between the initial point in the cluster of the kth ellipsometer detection points and the initial point with the maximum thickness is summed and averaged to obtain the average distance between the detection points in the cluster of the kth ellipsometer detection points.

[0043] This invention proposes a film thickness detection system based on an ellipsometer, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps of the film thickness detection method based on an ellipsometer as described above.

[0044] The beneficial effects of the technical solution of the present invention are:

[0045] This invention analyzes the reflectance data of initial points to obtain the clusters of ellipsometer detection points and the corresponding perovskite film structural characteristics, and then uses this information to determine several optimal target detection points. Based on these characteristics, the distribution of target detection points and their corresponding reflectance compensation results are determined, resulting in accurate film thickness data and eliminating ellipsometer detection errors caused by perovskite film surface structure issues. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 A flowchart illustrating a film thickness detection method based on an ellipsometer, provided as an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of a perovskite thin film formed by spin coating.

[0049] Figure 3 Example diagram of target detection points;

[0050] Figure 4 This is a structural diagram of a film thickness detection system based on an ellipsometer, provided as an embodiment of the present invention. Detailed Implementation

[0051] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a film thickness detection method based on an ellipsometer proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0053] The following description, in conjunction with the accompanying drawings, details a specific scheme for a film thickness detection method based on an ellipsometer provided by the present invention.

[0054] This invention provides a film thickness detection method and system based on an ellipsometer. Please refer to [link / reference]. Figure 1 The diagram illustrates a flowchart of a film thickness detection method based on an ellipsometer according to an embodiment of the present invention. The method includes the following steps:

[0055] S101. Obtain the initial point reflection data of the initial point set on the target perovskite film.

[0056] For example, the initial points are mainly distributed at the edges and central regions of the target perovskite film to ensure coverage of critical portions of the film. The edge locations are used to capture film inhomogeneities, while the central locations help analyze the overall uniformity of the film layer.

[0057] During spin coating or other film formation processes, the edge regions of perovskite films are susceptible to solvent evaporation and temperature changes, potentially resulting in thinner or uneven film thickness. Therefore, the edge locations are crucial, requiring the selection of several points along the film's edges as testing sites. Typically, the four edges of the target perovskite film can be chosen. The central portion of the target perovskite film is usually thicker and may exhibit different crystallization characteristics or film distribution. Selecting points in the central region helps analyze the overall uniformity of the target perovskite film; therefore, several points in the central area are usually selected for testing.

[0058] Optionally, the number of sampling points can be set according to actual needs. In a specific embodiment, it is 20. There is no specific limit here, but the number requirement must ensure that it can reflect the representative data of the target perovskite film.

[0059] The principle of the ellipsometer is as follows: the ellipsometer obtains the optical properties of the thin film by measuring the amplitude and phase changes of the reflected light.

[0060] The operating steps are as follows: Set an appropriate wavelength and incident angle. Align the ellipsometer probe with each detection point and collect the amplitude and phase data of the reflected light. Record the data for each point for subsequent analysis.

[0061] The data analysis process is as follows: Film thickness estimation: Combining amplitude and phase data, the film thickness at each point is calculated using ellipsometer software.

[0062] The specific initial point reflection data obtained mainly includes: Amplitude: the intensity change of the reflected light, reflecting the interaction strength between the thin film and the incident light; and Phase: the phase difference between the incident and reflected light, reflecting the propagation characteristics of light in the thin film.

[0063] S102. Determine the initial point cluster based on the reflective data of the initial point.

[0064] In this embodiment, the initial point cluster is determined based on the reflectance data of the initial points, specifically including:

[0065] Calculate the similarity value between the first initial point and the second initial point based on the reflectance data of the initial point.

[0066] When the similarity value is within the preset similarity threshold range, the first initial point and the second initial point are determined to be in the same cluster, and the cluster in which the first initial point and the second initial point are located is determined as the initial point cluster.

[0067] Here, the first initial point and the second initial point are any different initial points among the initial points.

[0068] In this embodiment, the initial point reflection data includes initial amplitude data and initial phase data. Based on the initial point reflection data, the similarity value between the first initial point and the second initial point is calculated, specifically including:

[0069] Calculate the Pearson correlation coefficient between the first initial point and the second initial point to obtain the initial point correlation between the first initial point and the second initial point;

[0070] Calculate the reciprocal of the difference between the initial phase data of the first initial point and the second initial point to obtain the phase correlation;

[0071] Calculate the product of the initial point correlation and the phase correlation and normalize it to obtain the similarity value.

[0072] For example, the ellipsometer generates a detection result at each initial point, namely, the reflected light data at that initial point. This reflected light data includes amplitude and phase. Amplitude data reflects the intensity of the reflected light; by comparing it with a model of the material's refractive index, the amplitude data can provide preliminary information about the film thickness. Phase data: The phase information of the reflected light helps determine the film thickness. Since the propagation of light waves within the film causes phase changes, measuring the phase difference of the reflected light can estimate the film thickness.

[0073] For example, the data format of amplitude and phase at different points can be represented as: ; ,in, Indicates the first The reflected amplitude at each initial point; Indicates the first Phase values ​​at each initial point.

[0074] Reflectance values ​​can indicate the basic characteristics of an initial point within a thin film, including the film thickness near that point. During the formation of perovskite thin films, physical factors can cause non-uniformity in film thickness across different regions. Therefore, the film thickness calculated using reflectance values ​​can be used as the film thickness near that point.

[0075] Specifically, in the spin-coating method for perovskite film formation, the film is often thicker at the center than at the edges due to solution rotation and solvent evaporation. This is because the evaporation rate of the solution is higher at the edges during spin-coating, while the central region contains more solution, making it easier to form a thicker film layer there. Therefore, the perovskite thin film to be tested exhibits the following thickness characteristics: the closer to the center of the film, the higher its thickness value, and the further away from the center, the thinner it tends to be (these characteristics are difficult to observe with the naked eye and can only be obtained using ellipsometer equipment).

[0076] like Figure 2 As shown, Figure 2 This is a schematic diagram of a perovskite thin film formed by spin coating. Figure 2 In the middle, the same distance (radius) from the center of the membrane. Within the inner circle, that is, the edge covered by a ring, the corresponding thickness values ​​are theoretically quite similar, i.e., the initial isothickness line. Points on an isothickness line can be considered as points in the same cluster because their distances from the center point are close. Therefore, different isothickness lines can be considered as different clusters. Thus, as long as the reflectance values ​​exhibit similarity, based on the shape and structural characteristics of the film, they must lie within the same isothickness line; conversely, the reflectance values ​​of points within the same isothickness line must also exhibit similarity. That is, within an isothickness line, the reflectance data of detection points show a high correlation. These two conditions are mutually necessary and sufficient.

[0077] Due to the limitations of the thin film's surface structure, multiple ellipsometer detection points are required to assess the overall film thickness based on the grid distribution results. However, an unreasonable distribution of detection points can lead to randomness in the thickness measurement, failing to capture the full picture of the film's surface thickness and its complete characteristics.

[0078] Therefore, in this embodiment, the focus is on using the initial point distribution and corresponding reflective properties to determine and adjust the subsequent point distribution, so that the detection points are all distributed in the equal thickness line, thereby improving the effect of the final detection result in reflecting the overall characteristics of the film thickness and improving the detection accuracy.

[0079] Specifically, firstly, we analyze the correlation reflected by the reflective data of different points in the initial points to determine the initial isothelium line (since points on an isothelium line can be regarded as points in the same cluster because their distances from the center point are close, different isothelium lines can be regarded as different clusters; therefore, the initial isothelium line here is the initial point cluster).

[0080] Get the Sequence of amplitude and phase information at each initial point: Each initial point possesses an information sequence. Starting from the sequence of the first detection point, the similarity value between it and other points (i.e., the similarity value between the first initial point and the second initial point) is calculated using the following formula:

[0081]

[0082] in, This represents the similarity value between the first initial point and the second initial point. This represents the reciprocal of the phase difference between the first and second initial points. This represents the Pearson correlation coefficient between the first and second initial points. This indicates the normalization method.

[0083] The similarity between the reflective sequences from the first and second initial points is quantified by calculating the Pearson correlation coefficient. The closer the value is to 1, the higher the similarity, and the more likely they are to lie on a line of equal thickness within the film. Similarly, the difference is inversely proportional to... The purpose of this coefficient is to amplify the weight of the phase value in the calculation of film thickness among the reflective parameters. This is because the phase information of reflected light is more reliable in determining film thickness than amplitude. Since the propagation of light waves within the film causes phase changes, measuring the phase difference of the reflected light can deduce the film thickness. A higher similarity value indicates a closer similarity in the phase values ​​of the reflective properties between the two initial detection points, and consequently, a closer similarity in the corresponding film thickness values. Furthermore, after obtaining the similarity value, the possible distribution of the initial points within the isothighting line is considered to place the similarity value within a specific range. The portion within the range is used as a reference point for the isopyreline and categorized into an initial point cluster. Generally, there are multiple initial point clusters because there are multiple isopyrelines within the film.

[0084] Optionally, in a specific embodiment, the preset similarity threshold range is: In other embodiments, the settings can be reset based on historical data experience. This is only a preferred example in this embodiment and is not specifically limited thereto.

[0085] S103. Based on the initial point cluster, determine the ellipsometry detection point cluster.

[0086] In this embodiment, the clustering of ellipsometer detection points is determined based on the initial point clustering, specifically including:

[0087] Determine the initial point of maximum thickness, and based on the initial points in each initial point cluster, determine the reflectivity of each initial point cluster;

[0088] When the reflectivity of the j-th initial point cluster meets the preset reflectivity threshold, the j-th initial point cluster is determined as the ellipsometer detection point cluster.

[0089] Based on the initial points in each initial point cluster, determine the reflectivity of each initial point cluster, specifically including:

[0090] Calculate the mean similarity of initial points in the cluster with the j-th initial point;

[0091] Calculate the average distance between initial points in the j-th initial point cluster and the initial point with the largest thickness.

[0092] The reflectivity correlation of the j-th initial point cluster is obtained by multiplying the mean initial point similarity of the j-th initial point cluster with the reciprocal of the mean initial point similarity of the j-th initial point cluster and then normalizing the result.

[0093] For example, the initial point with the maximum thickness is the initial point with the largest thickness data among the initial points.

[0094] In one specific embodiment, the distance characteristics between reference points are analyzed to obtain the degree of reflectivity. The distance characteristics between reference points refer to the distance from the thickest region (center region) of the film to the reflectivity data of initial points with high similarity, which are distributed along a line of equal thickness. It is relatively fixed, or has little variation.

[0095] In summary, to obtain the first For each initial point cluster, the distance values ​​between several initial reference points within the initial point cluster and the initial point with the largest thickness are obtained using machine vision (current technology, distance between points). .

[0096] When the distance values ​​of reference points within a cluster are similar or the same, they can be divided into an initial isothickness line (i.e., an initial point cluster). Specifically: obtain the first... Within the cluster of the initial point, the th... The mean similarity between the initial point and the initial point sequence within the initial point cluster. ,in, This indicates the index of the initial point within the initial point cluster, and the mean value refers to the average similarity value between this point and other points within the initial point cluster.

[0097] The formula for calculating the reflectivity of each initial point cluster, based on the initial points within each initial point cluster, can be as follows:

[0098]

[0099] in, Indicates the first The degree of reflectivity of the clusters at the initial points This represents the distances between two points within the initial cluster and the initial point with the maximum thickness, and the difference between the two distances is calculated (the first distance). The and the first indivual), This indicates the number of initial points within the initial point cluster.

[0100] When the initial points within the initial point cluster are all close to the initial point with the maximum thickness, the sum value The smaller the value, the larger the inverse ratio, and the smaller the mean of the initial point similarity. It is also relatively large (because the mean similarity of the initial points is also relatively large at this time). Within the corresponding clusters, the correlation of reflectivity of points within the cluster is relatively high. Based on the similarity characteristics of reflective data, if the distances are close, such initial points will be distributed along a line of equal thickness. Through the above-mentioned screening mechanism based on distance and similarity, detection points with thin film reflective properties were selected.

[0101] In one specific embodiment, when the reflectivity meets a preset reflectivity threshold... If the reflectivity is high, all initial points within the initial point cluster are marked as ellipsometer detection points constituting the initial isothickness line. Conversely, if the above range is not met, it proves that although the initial points have high similarity, they do not meet the film-forming characteristics of perovskite films in terms of distance distribution, so such reference points are abandoned and regarded as noise points.

[0102] Optionally, the preset reflectivity threshold here is only a good example. In the actual implementation process, it can be set and modified according to actual needs, or it can be calculated based on historical experience. No specific restrictions are imposed here.

[0103] Furthermore, all clusters that satisfy the initial isothropometric line (i.e., the initial point cluster) are obtained. The initial cluster points corresponding to these isothropometric lines are regarded as detection points, and these clusters that satisfy the initial isothropometric line are determined as ellipsometer detection point clusters. That is, after these points are detected by the ellipsometer, their corresponding film thickness values ​​are of reference value.

[0104] S104. Determine the spin coating distribution amount based on the cluster of ellipsometer detection points. When the spin coating distribution amount meets the preset rotational distribution amount threshold, determine the center point based on the cluster of ellipsometer detection points, and determine the target detection point based on the center point. When the spin coating distribution amount does not meet the preset rotational distribution amount threshold, determine the target perovskite film as a damaged perovskite film.

[0105] In this embodiment, the spin coating distribution is determined based on the clustering of ellipsometer detection points, specifically including:

[0106] Obtain the membrane thickness detection values ​​of all initial points in the cluster of ellipsometer detection points, and calculate the average membrane thickness of each detection point in each cluster of ellipsometer detection points.

[0107] Obtain the distances between all initial points in the ellipsometer detection point cluster and the initial point with the maximum thickness, and calculate the mean detection point distance for each ellipsometer detection point cluster.

[0108] The spin coating distribution is calculated based on the average film thickness of each cluster of ellipsometer detection points and the average distance between each cluster of ellipsometer detection points.

[0109] The spin coating distribution is calculated based on the average film thickness of each cluster of ellipsometer detection points and the average distance between each cluster of detection points. Specifically, this includes:

[0110] Calculate the difference between the average film thickness of the cluster at the (k+1)th ellipsometer detection point and the average film thickness of the cluster at the kth ellipsometer detection point, and take the absolute value of the difference to obtain the thickness difference of the nth adjacent cluster.

[0111] Calculate the difference between the mean distance between the clusters of the (k+1)th ellipsometer detection points and the mean distance between the clusters of the kth ellipsometer detection points, and take the absolute value of the difference to obtain the distance difference between the nth adjacent clusters.

[0112] Calculate the ratio of the distance difference between the nth and nth adjacent clusters to obtain the ratio of the nth difference;

[0113] Calculate the difference between the nth difference ratio and the preset empirical coefficient to obtain the nth theoretical spin coating distribution.

[0114] Calculate the sum and average of N theoretical spin coating distributions to obtain the average theoretical spin coating distribution.

[0115] The spin coating distribution is obtained by adding one to the mean of the theoretical spin coating distribution and then taking the reciprocal.

[0116] Obtain the membrane thickness detection values ​​of all initial points in the ellipsometer detection point cluster, and calculate the mean membrane thickness of each detection point in the ellipsometer detection point cluster, specifically including:

[0117] The average film thickness of the initial points in the cluster of the kth ellipsometer detection points is obtained by summing the film thickness values ​​of the initial points in the cluster of the kth ellipsometer detection points.

[0118] Obtain the distances between all initial points in each ellipsometer detection point cluster and the initial point with the maximum thickness, and calculate the mean distance of each detection point in each ellipsometer detection point cluster. Specifically, this includes:

[0119] The average distance between the initial point in the cluster of the kth ellipsometer detection points and the initial point with the maximum thickness is summed and averaged to obtain the average distance between the detection points in the cluster of the kth ellipsometer detection points.

[0120] For example, obtain the first (total) (Number) ellipsometer detection points are clustered together and their corresponding detection points are identified. The mean film thickness detection value of each detection point within the ellipsometer detection point cluster is obtained. and the average distance between detection points (The average of the sum of the distances from each detection point to the initial point of maximum thickness).

[0121] As the distance between the detection point and the center point decreases, the film thickness value of the detection point within the cluster of ellipsometer detection points will theoretically show an increasing trend. This is because processes such as spin coating often result in a thicker film in the center (due to the rotation of the solution and the evaporation of the solvent, the center of the film is often thicker than the edge), while the edge is thinner. Therefore, the measurement points should include the center and the surrounding edges of the film to ensure thickness data at different locations.

[0122] Therefore, the region exhibiting the aforementioned relationship between distance and film thickness represents a higher spin-coating distribution, which satisfies the general characteristics of perovskite thin films. Thus, when the proportionality between the two is high, in the direction from any detection point to the center point, as the distance between any detection point and the center point decreases, the spin-coating distribution increases accordingly. This type of region is more suitable for feedback distribution detection points because it possesses superior thin film characteristics.

[0123] Based on the clustering of ellipsometer detection points, the formula for calculating the spin coating distribution can be as follows:

[0124]

[0125] in, Indicates the amount of spin coating distribution. This represents the difference between the mean distances of the (k+1)th ellipsometer detection point cluster and the mean distance of the kth ellipsometer detection point cluster, with the absolute value of the difference taken to obtain the distance difference between the nth adjacent clusters. This means taking the difference between the mean film thickness of the cluster at the (k+1)th ellipsometer detection point and the mean film thickness of the cluster at the kth ellipsometer detection point, and then taking the absolute value of the difference to obtain the thickness difference of the nth adjacent cluster. This represents the preset empirical coefficient. This indicates the number of clusters of points detected by the ellipsometer, which is numerically equal to the number of theoretical spin-coating distributions. .

[0126] In the formula for calculating the distribution of spin coating, Indicates the proportion of the difference. This represents the theoretical spin coating distribution. This represents the average theoretical spin coating distribution.

[0127] By analyzing the ratio of the differences Once a direct proportional relationship is established between the two, then within different clusters, the resulting difference will always be consistent with the empirical coefficient. Similar, at this point, the difference between the difference ratio and the empirical coefficient is... The closer it is to 0, the higher the corresponding reflective spin coating distribution.

[0128] At the same time, when proportional, it also satisfies the basic morphological characteristics of perovskite thin films, that is, at this time, in this direction, the distance between the isothroat lines decreases and increases (isothroat lines) The line connecting an initial point and the initial point with the highest center thickness is the direction of the isothroat. All isothroat lines passing through this ray possess the morphological characteristics of a thin film (because this direction has the characteristic of being thicker in the middle and lower on both sides), and all meet the requirements for the arrangement of detection points, because this direction satisfies the preset rotation distribution threshold.

[0129] Therefore, in a specific embodiment, the preset rotation distribution threshold can be taken as... Furthermore, the preset rotation distribution threshold here is only a good example. In the actual implementation process, it can be set and modified according to actual needs, or it can be calculated based on historical experience. No specific restrictions are imposed here.

[0130] When the spin coating distribution meets the preset spin distribution threshold, the center point is determined based on the cluster of ellipsometer detection points. Specifically, different initial center points are determined based on each cluster of ellipsometer detection points, and the average of the position coordinates of all the initial center points is calculated to obtain the final center point. (Determining the center point of a circle based on any three points on the circle is an existing technology, and averaging the position coordinates of multiple initial center points to determine the center point is also an existing technology, which will not be elaborated on here.)

[0131] Determining the target detection point based on the center point can specifically involve: acquiring 36 rays at 10° intervals along the isopythmite line, with each ray at a distance of 10° from the center. ( (This represents the maximum distance from the center of the contour line) Draw a contour line to obtain the target detection point location confirmed by feedback. See the following for details. Figure 3 , Figure 3 This is an example image showing the target detection points. Figure 3 In this process, different isothickness lines are determined by spreading outward from the center point at equal intervals, and target detection points are set at fixed angles on each isothickness line to detect the target perovskite film.

[0132] S105. Obtain the reflectance data of the target detection point and evaluate the uniformity of the target perovskite film based on the reflectance data of the target detection point.

[0133] Several target detection points were obtained based on feedback. These points are the areas that the ellipsometer needs to detect in the future.

[0134] Acquire the corresponding reflectivity data to obtain reflectivity data for all detection points (including the initial point and subsequent target detection points), and establish a two-dimensional grid distribution with distance on the horizontal axis and thickness on the vertical axis. Use interpolation to supplement any undetected thickness areas.

[0135] The ellipsometer film thickness test results were obtained. Based on these results, the specific test points were determined through continuous feedback. While ensuring the basic appearance of the perovskite film, true and accurate film thickness test data were obtained, improving the test accuracy and practicality.

[0136] In summary, in this embodiment of the invention, by analyzing the reflective data of the initial points, the clusters of ellipsometer detection points and the corresponding perovskite film structural characteristics are obtained, and the optimal target detection points are determined based on the feedback. The distribution of target detection points and their corresponding reflective compensation results are determined according to these characteristics, resulting in accurate film thickness data and eliminating ellipsometer detection errors caused by perovskite film surface structure issues.

[0137] This invention also proposes a film thickness detection system based on an ellipsometer; please refer to [link / reference]. Figure 4 The diagram shows a structural diagram of a film thickness detection system based on an ellipsometer according to an embodiment of the present invention. The system includes: a data acquisition module 101, a data processing module 102, and a detection and analysis module 103.

[0138] The data acquisition module 101 is used to acquire the initial point reflection data of the initial point set on the target perovskite film;

[0139] The data processing module 102 is used to determine the initial point cluster based on the reflective data of the initial point; determine the ellipsometer detection point cluster based on the initial point cluster; determine the spin coating distribution amount based on the ellipsometer detection point cluster; when the spin coating distribution amount meets the preset rotational distribution amount threshold, determine the center point based on the ellipsometer detection point cluster, and determine the target detection point based on the center point; when the spin coating distribution amount does not meet the preset rotational distribution amount threshold, the target perovskite film is determined to be a damaged perovskite film.

[0140] The detection and analysis module 103 is used to acquire the reflectance data of the target detection point and evaluate the uniformity of the target perovskite film based on the reflectance data of the target detection point.

[0141] It should be noted that the system provided in the above embodiments is only an example of the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the computer device can be divided into different functional modules to complete all or part of the functions described above. In addition, the ellipsometer-based film thickness detection system and the ellipsometer-based film thickness detection method embodiment provided in the above embodiments belong to the same concept, and their specific implementation process can be found in the method embodiment, which will not be repeated here.

[0142] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0143] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0144] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A film thickness detection method based on an ellipsometer, characterized in that, include: Acquire the initial point reflection data of the initial point set on the target perovskite film; Based on the reflected light data of the initial points, calculate the similarity value between the first initial point and the second initial point; When the similarity value is within a preset similarity threshold range, the first initial point and the second initial point are determined to be in the same cluster, and the cluster in which the first initial point and the second initial point are located is determined as the initial point cluster. Wherein, the first initial point and the second initial point are any different initial points among the initial points; Determine the initial point of maximum thickness, and determine the reflectivity of each initial point cluster based on the initial points in each initial point cluster; When the reflectivity of the j-th initial point cluster meets the preset reflectivity threshold, the j-th initial point cluster is determined as the ellipsometer detection point cluster. Obtain the film thickness detection values ​​of all initial points in the cluster of ellipsometer detection points, and calculate the average film thickness of each detection point in each cluster of ellipsometer detection points. Obtain the distances between all initial points in the ellipsometer detection point cluster and the initial point with the maximum thickness, and calculate the average detection point distance for each ellipsometer detection point cluster. Calculate the difference between the average film thickness of the cluster at the (k+1)th ellipsometer detection point and the average film thickness of the cluster at the kth ellipsometer detection point, and take the absolute value of the difference to obtain the thickness difference of the nth adjacent cluster. Calculate the difference between the mean distance between the clusters of the (k+1)th ellipsometer detection points and the mean distance between the clusters of the kth ellipsometer detection points, and take the absolute value of the difference to obtain the distance difference between the nth adjacent clusters. Calculate the ratio of the distance difference between the nth adjacent clusters to the distance difference between the nth adjacent clusters to obtain the ratio of the nth difference; Calculate the difference between the nth difference ratio and the preset empirical coefficient to obtain the nth theoretical spin coating distribution. Calculate the sum and average of N theoretical spin coating distributions to obtain the average theoretical spin coating distribution. The spin coating distribution is obtained by adding one to the mean of the theoretical spin coating distribution and then taking the reciprocal. When the spin coating amount meets the preset rotational distribution amount threshold, the center point is determined according to the cluster of detection points of the ellipsometry, and the target detection point is determined according to the center point. When the spin coating amount does not meet the preset rotational distribution amount threshold, the target perovskite film is determined to be a damaged perovskite film. Acquire the reflectance data of the target detection point, and evaluate the uniformity of the target perovskite film based on the reflectance data of the target detection point.

2. The film thickness detection method based on an ellipsometer according to claim 1, characterized in that, The initial point reflection data includes initial amplitude data and initial phase data. The step of calculating the similarity value between the first initial point and the second initial point based on the initial point reflection data specifically includes: Calculate the Pearson correlation coefficient between the first initial point and the second initial point to obtain the initial point correlation between the first initial point and the second initial point; Calculate the reciprocal of the difference between the initial phase data of the first initial point and the second initial point to obtain the phase correlation; The product of the initial point correlation and the phase correlation is calculated and normalized to obtain the similarity value.

3. The film thickness detection method based on an ellipsometer according to claim 1, characterized in that, The step of determining the reflectivity correlation of each initial point cluster based on the initial points in each initial point cluster specifically includes: Calculate the mean similarity of initial points in the cluster with the j-th initial point; Calculate the average distance between initial points within the j-th initial point cluster and the initial point with the maximum thickness, based on the distances between the initial points in the j-th initial point cluster and the initial point with the maximum thickness. The reflectivity correlation of the j-th initial point cluster is obtained by multiplying the mean initial point similarity of the j-th initial point cluster with the reciprocal of the mean initial point similarity of the j-th initial point cluster and then normalizing the result.

4. The film thickness detection method based on an ellipsometer according to claim 1, characterized in that, The step of obtaining the film thickness detection values ​​of all initial points in the ellipsometer detection point cluster and calculating the average film thickness of each detection point in the ellipsometer detection point cluster specifically includes: The average film thickness of the initial points in the cluster of the kth ellipsometer detection points is obtained by summing the film thickness values ​​of the initial points in the cluster of the kth ellipsometer detection points.

5. The film thickness detection method based on an ellipsometer according to claim 1, characterized in that, The step of obtaining the distances between all initial points in the ellipsometer detection point cluster and the initial point with the maximum thickness, and calculating the average detection point distance for each ellipsometer detection point cluster, specifically includes: The average distance between the initial point in the cluster of the kth ellipsometer detection points and the initial point with the maximum thickness is summed and averaged to obtain the average distance between the detection points in the cluster of the kth ellipsometer detection points.

6. A film thickness detection system based on an ellipsometer, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the computer program is executed by the processor, it implements the steps of the film thickness detection method based on an ellipsometer as described in any one of claims 1-5.

Images