Efficient laser cleaning method and system for wafer surface cleaning

Abstract

The invention relates to the technical field of semiconductor device processing, in particular to an efficient laser cleaning method and system for wafer surface cleaning. The method comprises the steps of obtaining a surface image of a wafer; extracting an impurity region in the surface image of the wafer; analyzing morphological characteristics of the impurity region, and determining a characteristic impurity coefficient of the impurity region; analyzing color characteristics of the impurity region, and determining an organic residue coefficient of the impurity region; classifying the impurity regions based on the characteristic impurity coefficients and the organic residue coefficients to obtain a plurality of impurity categories; according to the impurity category of each impurity area, the initial laser cleaning power of the impurity area is adjusted, and corrected laser cleaning power is obtained; and determining an optimal cleaning path for wafer cleaning according to the corrected laser cleaning power and the path between the impurity regions. According to the invention, efficient cleaning of the surface of the wafer is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor device processing, and in particular to a high-efficiency laser cleaning method and system for cleaning wafer surfaces. Background Art

[0002] Wafers are the foundation and core of semiconductor integrated circuits. During the wafer production process, to ensure surface flatness, cleanliness, and good electrical performance from impurities such as particles, metals, and organic matter, and to prevent circuit failures such as short circuits and open circuits, wafer cleaning is required at almost every stage to remove impurities from the wafer surface. Therefore, wafer surface cleaning is a routine process.

[0003] The existing wafer cleaning method generally uses traditional wet cleaning, specifically using solvents, acids, surfactants and water to spray the wafer surface, and using different reagents to remove pollutants, organic matter and metal ion pollution on the wafer surface. However, this cleaning method will leave residual pollutants and cleaning fluid in the process of cleaning the pollutants on the wafer surface, and cannot completely remove metal particles. Therefore, in order to ensure the efficiency and completeness of wafer cleaning, in the existing wet cleaning process, laser dry cleaning is used to assist wet cleaning, so as to further remove the residual pollution on the wafer surface after wet cleaning, so as to achieve efficient cleaning of the wafer surface. Summary of the Invention

[0004] In order to solve the technical problem of residual contamination after existing wet cleaning, the purpose of the present invention is to provide an efficient laser cleaning method and system for cleaning wafer surfaces. The technical solutions adopted are as follows: In a first aspect, an embodiment of the present invention provides an efficient laser cleaning method for cleaning a wafer surface, the method comprising: Acquire a surface image of a wafer; extract an impurity region in the surface image of the wafer; Analyzing the morphological characteristics of the impurity region to determine a characteristic impurity coefficient of the impurity region; analyzing the color characteristics of the impurity region to determine an organic residue coefficient of the impurity region; and classifying the impurity region based on the characteristic impurity coefficient and the organic residue coefficient to obtain a plurality of impurity categories; According to the impurity category of each impurity area, the initial laser cleaning power of the impurity area is adjusted to obtain a corrected laser cleaning power; The optimal cleaning path for wafer cleaning is determined based on the corrected laser cleaning power and the path between the impurity areas.

[0005] Preferably, extracting the impurity region in the surface image of the wafer includes: Fitting the envelope of the grayscale histogram of the wafer surface image and determining the peak value on the envelope; Get the mean of each peak value as the grayscale value; The pixel point corresponding to the grayscale value is used as a seed point, and regional growth is performed based on the seed point to obtain multiple growth regions; and the other growth regions except the growth region with the largest area are used as impurity regions in the surface image of the wafer.

[0006] Preferably, the calculation formula of the characteristic impurity coefficient is: ; in, is the characteristic impurity coefficient of the nth impurity region; e is a natural constant; is the probability that a pixel with gray value g appears in the eight-neighborhood of all pixels with gray value G in the nth impurity region; is the probability of the pixel with gray value G appearing in the nth impurity area; is the logarithmic function with base 2.

[0007] Preferably, analyzing the color characteristics of the impurity region to determine the organic residue coefficient of the impurity region includes: The coefficient of variation of the grayscale values ​​of all pixels in the impurity area is taken as the organic residue coefficient of the impurity area.

[0008] Preferably, the impurity regions are classified based on the characteristic impurity coefficient and the organic residue coefficient to obtain multiple impurity categories, including: The characteristic impurity coefficient is used as the distance between the impurity regions, and the impurity regions are divided into two clusters. The cluster with the smallest variance of the grayscale values ​​of the pixels in the two clusters is used as the first impurity category; the cluster with the largest variance of the grayscale values ​​of the pixels in the two clusters is used as the impurity category to be assigned; The organic residue coefficient is used as the distance between the impurity regions in the impurity category to be assigned, and the impurity regions in the impurity category to be assigned are divided into two clusters as the second impurity category and the third impurity category.

[0009] Preferably, the method for obtaining the initial laser cleaning power of the impurity region is: The impurity region with the smallest area in each impurity category is used as the starting region, and the optimal laser cleaning power of the starting region is determined; the optimal laser cleaning power of the starting region is used as the initial laser cleaning power of the impurity region within the impurity category.

[0010] Preferably, adjusting the initial laser cleaning power of each impurity region according to the impurity category to obtain the corrected laser cleaning power includes: The power adjustment value of the impurity region is determined by taking the ratio of the area of ​​the impurity region to the area of ​​the starting region of the impurity category to which the impurity region belongs; The product of the power adjustment value of the impurity area and the initial laser cleaning power is used as the corrected laser cleaning power.

[0011] Preferably, determining the optimal cleaning path for wafer cleaning based on the corrected laser cleaning power and the path between the impurity regions includes: The first parameter value is a distance between two adjacent impurity regions in the cleaning path; the second parameter value is a difference in corrected laser cleaning power between two adjacent impurity regions in the cleaning path; and the first parameter value and the second parameter value are weighted and summed to obtain a third parameter value. The cleaning path of the wafer is continuously adjusted, and the cleaning path corresponding to the minimum third parameter value is used as the optimal cleaning path.

[0012] Preferably, the method for obtaining the optimal laser cleaning power of the starting area is: The laser cleaning power is gradually increased from 0, and the cleaning effect at the current laser cleaning power is manually judged. When the laser cleaning power is changed and the cleaning effect begins to remain unchanged, the initial laser cleaning power when it remains unchanged is used as the optimal laser cleaning power for the starting area.

[0013] In a second aspect, an efficient laser cleaning system for cleaning a wafer surface is provided, the system comprising the following modules: A region extraction module is used to obtain a surface image of the wafer and extract impurity regions from the surface image of the wafer; a feature analysis module configured to analyze the morphological features of the impurity region to determine a characteristic impurity coefficient of the impurity region; analyze the color features of the impurity region to determine an organic residue coefficient of the impurity region; and classify the impurity region based on the characteristic impurity coefficient and the organic residue coefficient to obtain a plurality of impurity categories; A power determination module is used to adjust the initial laser cleaning power of each impurity region according to the impurity category of each impurity region to obtain a corrected laser cleaning power; The path determination module is used to determine the optimal cleaning path for wafer cleaning based on the corrected laser cleaning power and the path between the impurity areas.

[0014] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a memory and a processor, wherein the memory stores executable code, and when the processor executes the executable code, it implements the various possible implementations of the first aspect.

[0015] In a fourth aspect, an embodiment of the present invention provides a computer program product, which includes: computer program code, which, when running on a computer, enables the computer to execute the method in the above-mentioned first aspect or any possible implementation of the first aspect.

[0016] In a fifth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed in a computer, the computer is caused to execute various possible implementations of the first aspect.

[0017] The embodiments of the present invention have at least the following beneficial effects: The present invention first extracts the impurity areas on the wafer surface so that only the impurity areas can be analyzed and cleaned during subsequent laser cleaning. The non-impurity areas do not need to be laser cleaned again. Laser cleaning of the non-impurity areas may cause wear on the wafer. Because impurities on the wafer surface include metal particles, chemical residues, and organic residues, metal particles have relatively obvious crystal features, which are manifested as higher grayscale values ​​in adjacent pixels on the image, and the overall grayscale value is relatively stable. Therefore, the characteristic impurity coefficient of the impurity region is determined by the morphological characteristics of the impurity region. This characteristic impurity coefficient represents the impurity coefficient of the metal particles. Chemical and organic residues are mainly on the wafer surface, and the overall grayscale performance is random and relatively irregular. Therefore, the color characteristics of the impurity region are analyzed to determine the organic residue coefficient. This organic residue coefficient represents the discrimination coefficient between chemical and organic residues. Based on the characteristic impurity coefficient and the organic residue coefficient, the impurity regions are classified separately to obtain multiple impurity categories. The types of impurity regions within each impurity category are more similar. In theory, the laser cleaning power should be the same for each impurity category. However, because the sizes of different impurity regions in the same impurity category are different, using the same initial power for cleaning can easily lead to slow cleaning speeds. Therefore, further, according to the impurity category to which each impurity region belongs, the initial laser cleaning power of each impurity region is adjusted to obtain a corrected laser cleaning power. Finally, based on the corrected laser cleaning power and the path between the impurity regions, the optimal cleaning path for wafer cleaning is determined to achieve efficient cleaning of the wafer surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A flow chart of a method for efficiently laser cleaning a wafer surface provided by one embodiment of the present invention; Figure 2 A flow chart of a method for obtaining impurity categories provided by one embodiment of the present invention; Figure 3 A system block diagram of an efficient laser cleaning system for wafer surface cleaning provided by one embodiment of the present invention; Figure 4 A schematic structural diagram of a computer device provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the following, in combination with the accompanying drawings and preferred embodiments, describes in detail the specific implementation method, structure, characteristics and effects of an efficient laser cleaning method and system for wafer surface cleaning proposed in accordance with the present invention.

[0021] In the following description, different references to "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, the particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0022] In the description of the embodiments of the present invention, unless otherwise specified, " / " means or, for example, A / B can mean A or B: "and / or" in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present invention, "multiple" refers to two or more than two.

[0023] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0024] Unless defined otherwise, 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 belongs.

[0025] The embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of the present invention are also applicable to similar technical problems.

[0026] The present invention provides a specific implementation method for a highly efficient laser cleaning method and system for wafer surface cleaning. This method is applicable to wafers that have already undergone wet cleaning. In this scenario, laser dry cleaning is used to supplement the existing wet cleaning process, further removing residual contamination from the wafer surface after wet cleaning, thereby achieving efficient cleaning of the wafer surface.

[0027] The following describes in detail a specific solution of an efficient laser cleaning method and system for cleaning wafer surfaces provided by the present invention in conjunction with the accompanying drawings.

[0028] See also Figure 1 , which shows a flowchart of a high-efficiency laser cleaning method for cleaning a wafer surface provided by one embodiment of the present invention, the method comprising the following steps: Step S100 , obtaining a surface image of a wafer; and extracting an impurity region in the surface image of the wafer.

[0029] The information acquisition module is used to acquire a high-definition image of the wafer surface and preprocess the high-definition image of the wafer surface to obtain a surface image of the wafer. The preprocessing of the high-definition image of the wafer surface includes preprocessing operations such as denoising and enhancement. The information acquisition module can be a camera.

[0030] When cleaning contaminants on the surface of a wafer, the traditional method is generally to use traditional wet cleaning, using different reagents to remove contaminants, organic matter and metal ion contamination on the surface of the wafer.

[0031] This cleaning process can result in the presence of residual dyes and cleaning fluid, and it can't effectively remove metal particles. During the natural air drying process after wet cleaning, sensors are used to collect surface information from the wet-cleaned wafer, obtaining a surface image. This surface image information is then analyzed to determine the optimal laser cleaning path, achieving wet residual cleaning of the wafer surface.

[0032] The main principle of using laser dry cleaning to remove surface contaminants from wafers is to use a high-energy laser beam to irradiate the contaminants on the surface of the wafer, and quickly heat, evaporate or peel off the contaminants through the photothermal effect. When using laser cleaning, excessive laser power will inevitably cause damage to the surface of the wafer, so it is necessary to use appropriate power to clean different impurity areas. However, because the different impurity areas on the surface of the wafer are of different sizes and the factors causing contamination are different, when there is no reasonable cleaning path, it is necessary to frequently adjust the power of the laser, which leads to low cleaning efficiency. Therefore, the present invention classifies different impurity areas based on the surface image of the wafer, and then plans the cleaning path of the wafer according to the classification results in combination with the wafer cleaning process to achieve efficient cleaning of the wafer surface.

[0033] First, the impurity areas on the wafer surface are determined, and then the impurity areas on the wafer surface are classified. Then, the initial laser cleaning power for different impurity cleaning is determined. Then, the morphological characteristics of each impurity area are combined with different initial powers to determine the laser cleaning path.

[0034] The process of using laser to clean impurities from the wafer surface is essentially a feedback adjustment process, that is, using the impurity information on the wafer surface as feedback, and then adjusting the laser power and path to achieve laser cleaning of impurities. On the surface of the wafer, impurities are randomly distributed, so before laser adjustment, it is necessary to first determine the impurity area on the wafer surface, that is, to determine the impurity area in the wafer surface image.

[0035] Because the types of impurities in the wafer are different, they are manifested in the surface image of the wafer as differences in grayscale values. Therefore, in an embodiment of the present invention, the region division of the impurities on the wafer surface is achieved by using a region growing algorithm of multiple seed points.

[0036] Extract the impurity area in the surface image of the wafer. Specifically: first obtain the grayscale histogram of the surface image of the wafer, then use the envelope algorithm to fit the envelope of the grayscale histogram, and use the local maximum method to determine all peaks on the fitted envelope, that is, fit the envelope of the grayscale histogram of the surface image of the wafer, and determine the peak on the envelope; for each peak, calculate the mean of all grayscale values ​​corresponding to each peak as the representative grayscale value; use the pixel point corresponding to the representative grayscale value as the seed point, and perform regional growth based on the seed point to obtain multiple growth areas; other growth areas outside the growth area with the largest area are regarded as the impurity area in the surface image of the wafer.

[0037] When extracting the impurity area in the surface image of the wafer, the growth area with the largest area is removed. This is because the surface structure of the wafer is simple, so the peak with the largest area in the grayscale histogram corresponds to the uncontaminated area, and the areas corresponding to different peaks are different impurity areas of the wafer. Therefore, different impurity areas can be obtained by using the regional growth algorithm of multiple seed points.

[0038] The surface image of the wafer is analyzed to obtain the contaminated area on the wafer surface, which is also the impurity area. In the subsequent steps, the impurity area is classified according to its performance and the cleaning power of each impurity area is predicted. Then, the predicted power is used to obtain the optimized wafer cleaning path.

[0039] Step S200, analyzing the morphological characteristics of the impurity region to determine the characteristic impurity coefficient of the impurity region; analyzing the color characteristics of the impurity region to determine the organic residue coefficient of the impurity region; classifying the impurity region based on the characteristic impurity coefficient and the organic residue coefficient to obtain multiple impurity categories.

[0040] Because the impurities on the wafer surface are not all of the same type, there may be different impurities such as particles, chemicals, metals, organic matter, etc., and different impurities have different structures, so when they are processed with the same laser power, it is very easy to damage the wafer or not clean it thoroughly. Therefore, the embodiment of the present invention analyzes the morphological characteristics and color characteristics of different impurity areas to achieve classification of different impurity areas.

[0041] In some embodiments, multiple impurity categories are obtained by analyzing the morphological characteristics and color characteristics of different impurity regions, that is, the above step S200 can be performed by Figure 2 The steps shown achieve: Step S210 , analyzing the morphological characteristics of the impurity region to determine a characteristic impurity coefficient of the impurity region.

[0042] Impurities on the wafer surface primarily consist of metal particles, chemical residues, and organic residues. Metal particles differ from chemical and organic residues in their distinct crystalline characteristics, manifesting as highly similar grayscale values ​​for adjacent pixels in the image, resulting in a relatively stable grayscale across the entire region. Chemical and organic residues, on the other hand, exhibit a random, irregular grayscale appearance, primarily distinguished by their varying grayscale values.

[0043] The characteristic impurity coefficient is primarily used to distinguish metal particle impurities. Compared to other impurities, such as chemical and organic residues, metal particle impurities have a more stable form and a more regular color. Characteristic distinction is achieved by calculating the characteristic impurity coefficient.

[0044] Taking the nth impurity region as an example, the characteristic impurity coefficient of the nth impurity region is The calculation formula is: ; Among them, e is a natural constant; is the probability that a pixel with gray value g appears in the eight-neighborhood of all pixels with gray value G in the nth impurity region; is the probability of the pixel with gray value G appearing in the nth impurity area; is the logarithmic function with base 2.

[0045] In the calculation formula of the characteristic impurity coefficient, the denominator represents the degree of disorder of all grayscale values ​​in the nth impurity region, that is, the complexity of the appearance of different grayscale values. If the nth impurity region is a metal particle region, the corresponding denominator is smaller, and vice versa. The construction of the numerator is based on the crystal characteristic of metal particles, that is, several adjacent pixels have highly similar grayscale values, so conditional probability is used to represent the grayscale value distribution around different pixels. As a weight to filter the high similarity of grayscale. Combining the above logic, we have the characteristic impurity coefficient The bigger, The greater the probability that an impurity region is contaminated by metal particles, the greater the probability that the impurity region is contaminated by metal particles, and vice versa.

[0046] Step S220 , analyzing the color characteristics of the impurity region to determine the organic residue coefficient of the impurity region.

[0047] The organic residue coefficient characterizes the chemical and organic residue distinction coefficient. It is used to distinguish impurity regions between chemical and organic residues. Chemical and organic residues on the wafer surface have a random, relatively irregular grayscale appearance, primarily distinguished by their grayscale values. Therefore, the present invention achieves this feature by utilizing the coefficient of variation corresponding to the grayscale values ​​of pixels within the impurity region to process and calculate different regions.

[0048] The coefficient of variation of the grayscale values ​​of all pixels in the impurity area is used as the organic residual coefficient of the impurity area. More specifically, the standard deviation of the grayscale values ​​of all pixels in the impurity area is used as the numerator, the mean of the grayscale values ​​of all pixels in the impurity area is used as the denominator, and the ratio formed by the numerator and the denominator is used as the organic residual coefficient of the impurity area.

[0049] In step S230 , the impurity regions are classified based on the characteristic impurity coefficient and the organic residue coefficient to obtain a plurality of impurity categories.

[0050] First, the characteristic impurity coefficient is used as the distance between impurity regions, and the impurity regions are divided into two clusters. The cluster with the smallest variance of the grayscale values ​​of the pixels in the two clusters is used as the first impurity category; more specifically: the k-means clustering algorithm is used to cluster the impurity regions based on the characteristic impurity coefficient as the distance between the impurity regions, and the value of k is set to 2.

[0051] Then, the cluster with the largest variance of the grayscale values ​​of the pixels in the two clusters is taken as the impurity category to be assigned; the organic residue coefficient is taken as the distance between the impurity areas in the impurity category to be assigned, and the impurity areas in the impurity category to be assigned are divided into two clusters as the second impurity category and the third impurity category.

[0052] The different impurity regions on the wafer surface are divided into three impurity categories, including: the first impurity category, the second impurity category and the third impurity category.

[0053] In step S300 , the initial laser cleaning power of each impurity region is adjusted according to the impurity category of each impurity region to obtain a corrected laser cleaning power.

[0054] The impurity regions on the wafer surface are divided into three different impurity categories. Theoretically, the laser cleaning power should be the same for each impurity category. However, because the sizes of different impurity regions within the same impurity category vary, using the same initial power for cleaning can easily result in slow cleaning speeds. Therefore, the present invention predicts and adjusts the laser cleaning power for each impurity region within each category.

[0055] Taking any impurity category among the three impurity categories as the target impurity category and the impurity area with the smallest area in the target impurity category as the starting area, the optimal laser cleaning power of the starting area is determined. The method for obtaining the optimal laser cleaning power of the starting area is more specific: the laser cleaning power is gradually increased from 0, and the cleaning effect under the current laser cleaning power is manually judged. When the laser cleaning power is changed and the cleaning effect begins to remain unchanged, the initial laser cleaning power when it remains unchanged is used as the optimal laser cleaning power of the starting area. The optimal laser cleaning power of the starting area is also the initial laser cleaning power of the impurity area within the impurity category to which the starting area belongs, that is, the initial laser cleaning power of the impurity area within the same impurity category is the same. It should be noted that the step size of the laser cleaning power increase is 1, and the laser cleaning power must not exceed the maximum power value, which is the maximum operating power value of the laser cleaning equipment.

[0056] Then, the initial laser cleaning power corresponding to each impurity category is obtained. Since the initial laser cleaning power is obtained for the impurity area with the smallest area in the category, the initial laser cleaning power is the minimum power corresponding to the current category. Based on the minimum power, the power is adjusted to obtain the corrected laser cleaning power for each impurity area.

[0057] In some embodiments of the present invention, the initial laser cleaning power for each impurity region is adjusted based on the impurity category to obtain a corrected laser cleaning power. Specifically, the ratio of the area of ​​the impurity region to the area of ​​the starting region of the impurity category to which the impurity region belongs is used as the power adjustment value for the impurity region; and the product of the power adjustment value for the impurity region and the initial laser cleaning power is used as the corrected laser cleaning power. It should be noted that in this embodiment of the present invention, the area of ​​a region refers to the number of pixels within the region.

[0058] In other embodiments of the present invention, the calculation formula for correcting the laser cleaning power is: ;in, is the corrected laser cleaning power of the nth impurity region; e is a natural constant; γ is the suppression coefficient; is the area of ​​the nth impurity region; is the area of ​​the starting region of the impurity category to which the nth impurity region belongs; is the power adjustment value of the nth impurity region; is the initial laser cleaning power of the nth impurity region. In the embodiment of the present invention, the suppression coefficient is 0. In other embodiments, the suppression coefficient can be set by the implementer according to actual conditions.

[0059] The modified laser cleaning power prediction for impurity regions in the embodiments of the present invention is determined by the ratio of the initial laser cleaning power within the same impurity category to the area corresponding to the impurity region. Because impurity regions within the same impurity category share the same contamination source, the embodiments of the present invention utilize the ratio of the area of ​​the impurity region to be predicted to the area of ​​the initial laser power within the impurity category as the power adjustment parameter for the predicted region. It should be noted that, because impurities can adhere in three dimensions, a suppression coefficient can also be used to limit the power to avoid damage to the wafer caused by excessive laser power.

[0060] The initial laser cleaning power of all impurity regions is adjusted in this way to obtain the corrected laser cleaning power of each impurity region.

[0061] Step S400 , determining an optimal cleaning path for wafer cleaning based on the corrected laser cleaning power and the path between the impurity regions.

[0062] Through steps S200 to S300, the corrected laser cleaning powers of different impurity areas are obtained respectively, and then the optimal cleaning path of laser cleaning is obtained by using the optimal algorithm. The main purpose of planning the cleaning path to clean the wafer is to minimize the overall cleaning time and minimize the number of adjustments to the laser cleaning power when cleaning impurities in different areas. That is, when determining the optimal cleaning path, there are two aspects to consider. One is the shortest time, because the size of all impurity areas on the wafer is fixed, that is, the speed of laser cleaning is fixed, then the cleaning time can only be minimized by reasonably arranging the cleaning path. Therefore, in the embodiment of the present invention, the shortest path is restricted between different impurity areas. Another aspect is that the number of adjustments to the overall laser cleaning power is minimized. In the embodiment of the present invention, it is represented by the cumulative sum of the differences in the total laser cleaning power for cleaning different areas.

[0063] The first parameter value is a distance between two adjacent impurity regions in the cleaning path; the second parameter value is a difference in the corrected laser cleaning power between the two adjacent impurity regions in the cleaning path, that is, the absolute value of the difference in the corrected laser cleaning power between the two adjacent impurity regions in the cleaning path is used as the second parameter value; and the first parameter value and the second parameter value are weighted and summed to obtain a third parameter value. The absolute value of the difference between the corrected laser cleaning powers of two adjacent impurity regions in the cleaning path may also be rounded down, and the rounded-down result value may be used as the second parameter value.

[0064] The cleaning path of the wafer is continuously adjusted, and the cleaning path corresponding to the minimum third parameter value is used as the optimal cleaning path.

[0065] This can also be understood as constructing an objective function based on the path between the corrected laser cleaning power and the impurity region to determine the optimal cleaning path for wafer cleaning. The goal of obtaining the optimal cleaning path is to minimize the overall cleaning time and minimize the number of laser cleaning power adjustments required to clean impurities in different regions. Therefore, the objective function can be established based on these two requirements.

[0066] The formula of the objective function is: ;in, is the objective function value; min is the minimum value function; is the path weight coefficient; is the power weight coefficient; N is the number of impurity regions; is the coordinate of the nth impurity area being cleaned in the current path; The coordinates of the next impurity area to be cleaned; Corrected laser cleaning power for the next impurity area to be cleaned; is the objective function value corresponding to the cth cleaning path of the wafer. The cleaning path with the shortest duration is taken as the optimal cleaning path.

[0067] The path weight coefficient and the power weight coefficient are used to balance the importance of path length and power regulation. In the embodiment of the present invention, the values ​​of the path weight coefficient and the power weight coefficient are both 1.

[0068] The constraints of the objective function are: (1) each impurity region must be visited once and only once; (2) .

[0069] The objective function is solved, and the cleaning path corresponding to the minimum value obtained is the optimal cleaning path for wafer cleaning.

[0070] Therefore, the purpose of the constraint conditions of the objective function here is: 1. To avoid wafer loss caused by multiple stops and multiple cleanings between different areas during laser cleaning; 2. To enable areas with similar laser cleaning power to be cleaned with the same power, avoiding multiple ineffective adjustments of the laser cleaning power.

[0071] Correspondingly, it can also be understood that the purpose of determining the first parameter value is to avoid wafer loss caused by multiple stops and multiple cleanings between different areas during laser cleaning; the purpose of determining the second parameter value is to enable areas with similar laser cleaning power to be cleaned with the same power, avoiding multiple ineffective adjustments of the laser cleaning power.

[0072] The algorithm used to solve the above objective function is the particle swarm optimization algorithm, which will not be described in detail here. The particle swarm optimization algorithm is used to solve the objective function and obtain the optimal cleaning path for wafer cleaning.

[0073] After obtaining the optimal cleaning path for laser cleaning the wafer, the surface laser cleaning of the wafer is carried out according to the optimal cleaning path. The specific steps of laser cleaning the wafer are as follows: First, perform equipment inspection to ensure the normal operation of the laser cleaning equipment, including the laser, optical system and safety protection devices; Second, wafer positioning is performed to place the wafer on the cleaning table to ensure that it is fixed and stable to avoid movement during the cleaning process; Third, information is collected, images of the wafer surface are collected and preprocessed to obtain the surface image of the wafer and the impurity area on the wafer surface; Fourth, perform power prediction and path calculation: According to the above method, the corrected laser cleaning power and the optimal cleaning path during the wafer cleaning process are obtained; Fifth, wafer cleaning is performed by using the corrected laser cleaning power and the optimal cleaning path to perform laser spot scanning cleaning on different impurity areas; Sixth, cooling: After cleaning, allow the wafer to cool naturally to avoid thermal stress caused by rapid temperature drop. Seventh, conduct testing, using a microscope or other testing equipment to check the cleaning effect and confirm whether the contaminants have been effectively removed; Eighth, record data and record the parameters and test results during the cleaning process for subsequent analysis and improvement.

[0074] In summary, the present invention relates to the field of semiconductor device processing technology. This method predicts and corrects the laser cleaning power by analyzing the impurity region of the wafer, obtains the corrected laser cleaning power and the optimal cleaning path for wafer cleaning, and thereby achieves the operation of cleaning the wafer surface.

[0075] See also Figure 3 , which shows an efficient laser cleaning system for wafer surface cleaning provided by one embodiment of the present invention, the system includes the following modules: The region extraction module 10 is used to obtain a surface image of the wafer and extract the impurity region in the surface image of the wafer; a feature analysis module 20 configured to analyze the morphological features of the impurity region to determine a characteristic impurity coefficient of the impurity region; analyze the color features of the impurity region to determine an organic residue coefficient of the impurity region; and classify the impurity region based on the characteristic impurity coefficient and the organic residue coefficient to obtain a plurality of impurity categories; A power determination module 30 is configured to adjust the initial laser cleaning power of each impurity region according to the impurity category of each impurity region to obtain a corrected laser cleaning power; The path determination module 40 is used to determine the optimal cleaning path for wafer cleaning according to the modified laser cleaning power and the path between the impurity regions.

[0076] Optionally, the transmission medium may be a wired link, such as but not limited to coaxial cable, optical fiber, and digital subscriber line, or a wireless link, such as but not limited to Wireless Fidelity (WIFI), Bluetooth, and mobile device network.

[0077] It should be noted that the device provided in the above embodiment is only illustrated by the division of the above functional modules. In actual 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.

[0078] Figure 4FIG. 1 is a schematic diagram of the structure of a computer device provided by an embodiment of the present invention. For example, Figure 4 As shown, the computer device 500 includes: a memory 510, a processor 520, and a computer program 530 stored in the memory 510 and running on the processor 520, wherein when the processor 520 executes the computer program 530, the computer device can execute any of the efficient laser cleaning methods for wafer surface cleaning introduced above.

[0079] In addition, an embodiment of the present invention also protects a device, which may include a memory and a processor, wherein the memory stores executable program code, and the processor is used to call and execute the executable program code to execute the efficient laser cleaning method for wafer surface cleaning provided by an embodiment of the present invention.

[0080] In embodiments of the present invention, the device may be divided into functional modules based on the above-described method examples. For example, these modules may correspond to individual functional modules, or two or more functions may be integrated into a single processing module. The integrated modules may be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and represents only a logical functional division. In actual implementation, other division methods may be employed.

[0081] In the case of dividing each module into modules corresponding to each function, the device may further include a signal uploading module, a determination module, an adjustment module, etc. It should be noted that all relevant contents of each step involved in the above method embodiment can be referred to the functional description of the corresponding functional module and will not be repeated here.

[0082] It should be understood that the device provided by the embodiment of the present invention is used to perform the above-mentioned efficient laser cleaning method for cleaning the wafer surface, and thus can achieve the same effect as the above-mentioned implementation method.

[0083] When an integrated unit is employed, the device may include a processing module and a storage module. When the device is applied to a device, the processing module can be used to control and manage the device's operations. The storage module can be used to support the device in executing program code, etc. The processing module can be a processor or controller that can implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the present disclosure. The processor can also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a digital signal processor (DSP) and a microprocessor, etc. The storage module can be a memory.

[0084] In addition, the device provided in an embodiment of the present invention can specifically be a chip, component or module, and the chip may include a connected processor and memory; wherein the memory is used to store instructions, and when the processor calls and executes the instructions, the chip can execute the efficient laser cleaning method for wafer surface cleaning provided in the above embodiment.

[0085] An embodiment of the present invention also provides a computer-readable storage medium, which stores computer program code. When the computer program code is run on a computer, the computer executes the above-mentioned related method steps to implement the efficient laser cleaning method for wafer surface cleaning provided in the above embodiment.

[0086] An embodiment of the present invention also provides a computer program product. When the computer program product is run on a computer, it enables the computer to execute the above-mentioned related steps to implement the efficient laser cleaning method for wafer surface cleaning provided by the above embodiment.

[0087] Among them, the device, computer-readable storage medium, computer program product or chip provided in the embodiments of the present invention are all used to execute the corresponding methods provided above. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects in the corresponding methods provided above, and will not be repeated here. Through the description of the above implementation methods, technical personnel in the relevant field can understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In the embodiments provided by the present invention, it should be understood that the disclosed device and method can be implemented in other ways.

[0088] The device embodiments described above are merely illustrative. For example, the division into modules or units represents only one logical functional division. Actual implementations may employ alternative divisions, such as combining or integrating multiple units or components into another device, or omitting or disabling certain features. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through an interface, or indirect coupling or communication connection between devices or units may be electrical, mechanical, or otherwise.

[0089] It should also be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or terminal device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or terminal device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or terminal device comprising the element.

[0090] It should be noted that the order in which the embodiments of the present invention are described above is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0091] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0092] The above content is only a specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An efficient laser cleaning method for wafer surface cleaning, characterized in that: The method comprises the following steps: Acquire a surface image of a wafer; extract an impurity region in the surface image of the wafer; Analyzing the morphological characteristics of the impurity region to determine a characteristic impurity coefficient of the impurity region; analyzing the color characteristics of the impurity region to determine an organic residue coefficient of the impurity region; and classifying the impurity region based on the characteristic impurity coefficient and the organic residue coefficient to obtain a plurality of impurity categories; According to the impurity category of each impurity area, the initial laser cleaning power of the impurity area is adjusted to obtain a corrected laser cleaning power; The optimal cleaning path for wafer cleaning is determined based on the corrected laser cleaning power and the path between the impurity areas.

2. The high-efficiency laser cleaning method for wafer surface cleaning according to claim 1, characterized in that: The step of extracting the impurity region from the surface image of the wafer includes: Fitting the envelope of the grayscale histogram of the wafer surface image and determining the peak value on the envelope; Get the mean of each peak value as the grayscale value; The pixel point corresponding to the grayscale value is used as a seed point, and regional growth is performed based on the seed point to obtain multiple growth regions; and the other growth regions except the growth region with the largest area are used as impurity regions in the surface image of the wafer.

3. The high-efficiency laser cleaning method for wafer surface cleaning according to claim 1, characterized in that: The calculation formula of the characteristic impurity coefficient is: ； in, is the characteristic impurity coefficient of the nth impurity region; e is a natural constant; is the probability that a pixel with gray value g appears in the eight-neighborhood of all pixels with gray value G in the nth impurity region; is the probability of the pixel with gray value G appearing in the nth impurity area; is the logarithmic function with base 2.

4. The high-efficiency laser cleaning method for wafer surface cleaning according to claim 1, characterized in that: The analyzing the color characteristics of the impurity region to determine the organic residue coefficient of the impurity region includes: The coefficient of variation of the grayscale values ​​of all pixels in the impurity area is taken as the organic residue coefficient of the impurity area.

5. The high-efficiency laser cleaning method for wafer surface cleaning according to claim 1, characterized in that: The impurity regions are classified based on the characteristic impurity coefficient and the organic residue coefficient to obtain multiple impurity categories, including: The characteristic impurity coefficient is used as the distance between the impurity regions, and the impurity regions are divided into two clusters. The cluster with the smallest variance of the grayscale values ​​of the pixels in the two clusters is used as the first impurity category; the cluster with the largest variance of the grayscale values ​​of the pixels in the two clusters is used as the impurity category to be assigned; The organic residue coefficient is used as the distance between the impurity regions in the impurity category to be assigned, and the impurity regions in the impurity category to be assigned are divided into two clusters as the second impurity category and the third impurity category.

6. The high-efficiency laser cleaning method for wafer surface cleaning according to claim 1, characterized in that: The method for obtaining the initial laser cleaning power of the impurity region is as follows: The impurity region with the smallest area in each impurity category is used as the starting region, and the optimal laser cleaning power of the starting region is determined; the optimal laser cleaning power of the starting region is used as the initial laser cleaning power of the impurity region within the impurity category.

7. The high-efficiency laser cleaning method for wafer surface cleaning according to claim 6, characterized in that: The initial laser cleaning power of each impurity region is adjusted according to the impurity category of each impurity region to obtain a corrected laser cleaning power, including: The power adjustment value of the impurity region is determined by taking the ratio of the area of ​​the impurity region to the area of ​​the starting region of the impurity category to which the impurity region belongs; The product of the power adjustment value of the impurity area and the initial laser cleaning power is used as the corrected laser cleaning power.

8. The high-efficiency laser cleaning method for wafer surface cleaning according to claim 1, characterized in that: The method of determining an optimal cleaning path for wafer cleaning based on the corrected laser cleaning power and the path between the impurity regions includes: The first parameter value is a distance between two adjacent impurity regions in the cleaning path; the second parameter value is a difference in corrected laser cleaning power between two adjacent impurity regions in the cleaning path; and the first parameter value and the second parameter value are weighted and summed to obtain a third parameter value. The cleaning path of the wafer is continuously adjusted, and the cleaning path corresponding to the minimum third parameter value is used as the optimal cleaning path.

9. The high-efficiency laser cleaning method for wafer surface cleaning according to claim 6, characterized in that: The method for obtaining the optimal laser cleaning power of the starting area is: The laser cleaning power is gradually increased from 0, and the cleaning effect at the current laser cleaning power is manually judged. When the laser cleaning power is changed and the cleaning effect begins to remain unchanged, the initial laser cleaning power when it remains unchanged is used as the optimal laser cleaning power for the starting area.

10. An efficient laser cleaning system for wafer surface cleaning, characterized in that: The system includes the following modules: A region extraction module is used to obtain a surface image of the wafer and extract impurity regions from the surface image of the wafer; a feature analysis module, configured to analyze the morphological features of the impurity region to determine a characteristic impurity coefficient of the impurity region; and to analyze the color features of the impurity region to determine an organic residue coefficient of the impurity region; The impurity regions are classified based on the characteristic impurity coefficient and the organic residue coefficient to obtain multiple impurity categories; A power determination module is used to adjust the initial laser cleaning power of each impurity region according to the impurity category of each impurity region to obtain a corrected laser cleaning power; The path determination module is used to determine the optimal cleaning path for wafer cleaning based on the corrected laser cleaning power and the path between the impurity areas.

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