Wafer center alignment adjusting method and device and thin film deposition equipment

Abstract

The invention discloses a wafer center alignment adjusting method and device and thin film deposition equipment, and the method comprises the steps: obtaining an edge image collected by an image collection device, and the edge image comprises an edge image of a wafer and an edge image of a pedestal; extracting feature points in the edge image of the wafer to obtain wafer edge feature points, and generating a circle center of the wafer according to the wafer edge feature points; extracting feature points in the edge image of the base to obtain edge feature points of the base, and generating a circle center of the base according to the edge feature points; and calculating an eccentric value according to the circle center of the wafer and the circle center of the base, and transmitting the eccentric value to a manipulator, so that the manipulator adjusts the wafer according to the eccentric value, and the center of the wafer is aligned with the center of the base. According to the invention, the alignment accuracy of the center of the wafer and the center of the base is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method and device for adjusting the alignment of the center of a wafer and a thin film deposition apparatus. Background Art

[0002] In semiconductor manufacturing, a robotic arm is usually used to transfer a wafer to a process chamber and place the wafer on a pedestal. To ensure that after the wafer is processed, the thickness, uniformity, and stress of the thin film on the wafer surface reach the optimum, the center of the wafer needs to coincide exactly with the center of the pedestal, that is, the wafer and the pedestal are concentric. If the wafer and the pedestal are not concentric, that is, eccentric, it will lead to a decrease in the yield of the wafer and even cause the wafer to break and be scrapped.

[0003] In the related art, the operator relies on observing through a transparent cover plate whether the wafer is eccentric. If it is eccentric, the operator needs to estimate the eccentric value and adjust the wafer transfer position of the robotic arm accordingly. However, this method is relatively dependent on the operator's experience, and the results of each adjustment may be inconsistent, with low accuracy. Summary of the Invention

[0004] Embodiments of the present invention provide a method and device for adjusting the alignment of the center of a wafer and a thin film deposition apparatus, aiming to solve the problem of low accuracy in adjusting the alignment of the center of the existing wafer.

[0005] In a first aspect, the present invention provides a method for adjusting the alignment of the center of a wafer, the method comprising:

[0006] Obtaining an edge picture collected by an image acquisition device, wherein the edge picture includes an edge image of the wafer and an edge image of the pedestal;

[0007] Extracting feature points in the edge image of the wafer to obtain wafer edge feature points, and generating the center of the wafer according to the wafer edge feature points;

[0008] Extracting feature points in the edge image of the pedestal to obtain pedestal edge feature points, and generating the center of the pedestal according to the edge feature points;

[0009] Calculating an eccentricity value according to the center of the wafer and the center of the pedestal, and transmitting the eccentricity value to the robotic arm, so that the robotic arm adjusts the wafer according to the eccentricity value to align the center of the wafer with the center of the pedestal.

[0010] In a second aspect, the present invention further provides an apparatus for adjusting the alignment of the center of a wafer, the apparatus comprising:

[0011] An image acquisition device, which is arranged on the cover plate;

[0012] A calculation module, which is connected to the image acquisition device, and is configured to calculate an eccentricity value according to the edge pictures acquired by the image acquisition device, wherein the edge pictures include the edge image of the wafer and the edge image of the base;

[0013] A manipulator, which is connected to the calculation module, and is configured to adjust the wafer according to the eccentricity value so that the center of the wafer is aligned with the center of the base.

[0014] In a third aspect, the present invention further provides a thin film deposition apparatus, including a chamber and a base. After a wafer is introduced into the chamber and placed on the base, the wafer is adjusted by the wafer center alignment adjustment device described in the second aspect above and the wafer center alignment adjustment method described in the first aspect above to align the center of the wafer with the center of the base.

[0015] The present invention provides a method, apparatus and thin film deposition apparatus for aligning the center of a wafer. The wafer center alignment adjustment apparatus includes: an image acquisition device disposed on a cover plate; a calculation module connected to the image acquisition device, and the calculation module is configured to calculate an eccentricity value according to the edge pictures acquired by the image acquisition device, wherein the edge pictures include the edge image of the wafer and the edge image of the base; a manipulator connected to the calculation module, and the manipulator is configured to adjust the wafer according to the eccentricity value so that the center of the wafer is aligned with the center of the base. The wafer center alignment adjustment method includes: acquiring edge pictures acquired by the image acquisition device, wherein the edge pictures include the edge image of the wafer and the edge image of the base; extracting feature points in the edge image of the wafer to obtain wafer edge feature points, and generating the center of the wafer according to the wafer edge feature points; extracting feature points in the edge image of the base to obtain base edge feature points, and generating the center of the base according to the edge feature points; calculating an eccentricity value according to the center of the wafer and the center of the base, and transmitting the eccentricity value to the manipulator so that the manipulator adjusts the wafer according to the eccentricity value to align the center of the wafer with the center of the base. In this application, first, edge pictures are acquired by the image acquisition device, including the edge image of the wafer and the edge image of the base; then, the calculation module calculates the eccentricity value according to the edge image of the wafer and the edge image of the base; finally, the manipulator adjusts the wafer according to the calculated eccentricity value so that the center of the wafer is aligned with the center of the base. Compared with estimating the eccentricity value by human eye observation and adjusting the wafer, this application improves the accuracy when aligning the center of the wafer with the center of the base. Description of the Drawings

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 Shows a block schematic diagram of the adjustment device for wafer center alignment according to an embodiment of the present invention;

[0018] Figure 2 Shows a schematic structural diagram of the bottom surface of the cover plate of the adjustment device for wafer center alignment according to an embodiment of the present invention;

[0019] Figure 3 Shows a schematic structural diagram of the top surface of the cover plate of the adjustment device for wafer center alignment according to an embodiment of the present invention;

[0020] Figure 4 Shows a schematic flow chart of the steps of the adjustment method for wafer center alignment according to an embodiment of the present invention;

[0021] Figure 5 Shows a schematic diagram of the shooting range of the image acquisition module, the edges of the wafer and the base, and the feature points of the edges of the wafer and the base according to an embodiment of the present invention;

[0022] Figure 6 Shows a schematic flow chart of the steps of the adjustment method for wafer center alignment according to another embodiment of the present invention;

[0023] Figure 7 Shows a simple schematic diagram of a thin film deposition device according to an embodiment of the present invention.

[0024] Reference numerals:

[0025] 10. Cover plate; 11. Spray holes; 12. Image acquisition module; 13. Hand valve; 14. Handle; 20. Adjustment device for wafer center alignment; 21. Image acquisition device; 22. Calculation module; 23. Manipulator. Detailed implementation manners

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0027] The directional terms mentioned in the present invention, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "side", etc., are only references to the directions in the attached drawings. Therefore, the directional terms used are for explaining and understanding the present invention, rather than for limiting the present invention. In addition, in the drawings, structures that are similar or identical are denoted by the same reference numerals.

[0028] An embodiment of the present invention provides a method, device and thin film deposition equipment for adjusting the center alignment of a wafer, which solves the problem of low accuracy in adjusting the center alignment of an existing wafer. An edge image is collected by an image acquisition device, including an edge image of the wafer and an edge image of the base; then, an eccentricity value is calculated by a calculation module according to the edge image of the wafer and the edge image of the base; finally, a manipulator adjusts the wafer according to the calculated eccentricity value so that the center of the wafer is aligned with the center of the base, improving the accuracy of adjusting the alignment of the center of the wafer with the center of the base.

[0029] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0030] Please refer to Figure 1 , Figure 1 which shows a schematic diagram of the device for adjusting the center alignment of a wafer according to an embodiment of the present invention. As Figure 1 shown, the device 20 for adjusting the center alignment of the wafer includes an image acquisition device 21, a calculation module 22 and a manipulator 23. Among them, the image acquisition device 21 is arranged on the cover plate 10; the calculation module 22 is connected to the image acquisition device 21, and the calculation module 22 is used to calculate the eccentricity value according to the edge image collected by the image acquisition device 21, where the edge image includes an edge image of the wafer and an edge image of the base; the manipulator 23 is connected to the calculation module 22, and the manipulator 23 is used to adjust the wafer according to the eccentricity value so that the center of the wafer is aligned with the center of the base. It can be understood that the image acquisition device 21 is arranged on the bottom surface of the cover plate 10. It should be noted that in this embodiment, the image acquisition module 12 is communicatively connected to the calculation module 22, and the communication connection method is Bluetooth. In other embodiments, the communication connection method can also be a wireless connection method such as WiFi.

[0031] Specifically, please refer to Figure 2, a spray hole 11 is provided in a ring on the cover plate 10, and the image acquisition device 21 includes a plurality of image acquisition modules 12, and the plurality of image acquisition modules 12 are arranged at intervals at the outer ring formed by the spray holes 11. More specifically, the image acquisition module 12 includes a camera and a light source. Among them, the camera is used to acquire the edge picture, and the light source is used to make the quality of the edge picture acquired by the camera better. It should be noted that in this embodiment, the number of the image acquisition modules 12 is at least 2. Preferably, as Figure 2 shown, the number of the image acquisition modules 12 is 3, and the 3 image acquisition modules 12 are evenly arranged at intervals at the outer ring formed by the spray holes 11 to better acquire the edges of the wafer and the base. In other embodiments, the number of the image acquisition modules can also be 4, and the 4 image acquisition modules 12 are evenly arranged at intervals at the outer ring formed by the spray holes 11. It can be understood that the number of the image acquisition modules 12 is not specifically limited and is set according to actual needs. The camera is an industrial camera to improve the accuracy of acquiring the edges of the wafer and the base. It should also be noted that in this embodiment, the spray holes 11 are provided in a ring on the cover plate 10 and have the same aperture. The reason for setting the spray holes 11 is to make the intake air more uniform; the camera and the light source are arranged at the outer ring formed by the spray holes 11 to better acquire the edge picture.

[0032] Specifically, please refer to Figure 3 , a hand valve 13 and a handle 14 are provided on the top surface of the cover plate 10. The hand valve 13 is connected to an external air source to adjust the flow rate of the external air source. Slowly open the hand valve 13, and the camera can take pictures of the edges of the wafer and the base when the air is introduced, so as to judge whether the wafer will shift when the air is introduced. After the wafer processing is completed, close the hand valve 13 and the gate valve of the exhaust pipeline, take out the wafer, slowly open the hand valve 13 after disconnecting the external air source to backfill the cavity to the atmospheric state, and remove the cover plate 10 through the handle 14. It should be noted that in this embodiment, the number of the handles 14 is 2, which are symmetrically arranged on the cover plate 10 and are arranged at the edge of the cover plate 10. In other embodiments, the number and position of the handles 14 can also be set according to actual conditions. It should also be noted that in this embodiment, when the air is introduced, the calculation module 22 calculates the eccentricity value through the edge picture acquired by the image acquisition device 21 to observe whether the airflow moves the wafer when the air is introduced, and when the air is not introduced, it is to observe whether the wafer and the base are centered.

[0033] An embodiment of the present invention also provides a method for adjusting the center alignment of a wafer. This method for adjusting the center alignment of a wafer can be used in the device for adjusting the center alignment of a wafer in the above embodiment. The device for adjusting the center alignment of a wafer has been described in detail in the above embodiment. For the sake of simplicity of the specification, it will not be repeated here. To clearly illustrate the working process of the embodiment of the present invention, the method for adjusting the center alignment of a wafer will be described below in combination with the device for adjusting the center alignment of a wafer in the above embodiment. Referring to Figure 4 , the method for adjusting the center alignment of the wafer includes steps: S110 - S140.

[0034] S110. Obtain the edge picture collected by the image acquisition device, where the edge picture includes the edge image of the wafer and the edge image of the base.

[0035] In this embodiment, the image acquisition device collects the edge picture, where the edge picture includes the edge image of the wafer and the edge image of the base, and transmits the edge picture to the calculation module so that the calculation module calculates the eccentricity value according to the edge picture. It should be noted that, please refer to Figure 5 , which shows the shooting range of the camera and the edges of the wafer and the base when the number of image acquisition modules is 3.

[0036] S120. Extract the feature points in the edge image of the wafer to obtain the wafer edge feature points, and generate the center of the wafer according to the wafer edge feature points.

[0037] In this embodiment, the calculation module extracts the feature points in the edge image of the wafer to obtain the wafer edge feature points. Specifically, preprocess the edge image of the wafer to obtain the processed edge image of the wafer, where the preprocessing includes graying and Gaussian filtering denoising. Graying is to convert the color edge image of the wafer into a gray edge image of the wafer. Gaussian filtering denoising uses a Gaussian filter to smooth the gray edge image of the wafer to suppress high-frequency noise; perform gradient calculation on the processed edge image of the wafer to obtain the wafer gradient; perform non-maximum suppression processing on the wafer gradient to obtain the refined wafer image; perform double-threshold detection and edge connection on the refined wafer image to obtain the binary wafer edge image; perform feature point extraction on the binary wafer edge image to obtain the wafer edge feature points.

[0038] It should be noted that for the edge image of the processed wafer, gradient calculation is mainly performed to calculate the horizontal wafer gradient, vertical wafer gradient, as well as the magnitude and direction of the gradient to obtain the wafer gradient. Among them, the wafer gradient includes the wafer gradient magnitude and wafer gradient direction. During the calculation process, the wafer gradient magnitude and wafer gradient direction are obtained by calculating the gradient magnitude and direction of each pixel in the edge image of the processed wafer, so as to characterize the intensity and direction of the wafer edge. It should also be noted that non-maximum suppression processing is performed on the wafer gradient to refine the wafer gradient edge to a single-pixel width and avoid wide-edge interference. Specifically, for each pixel in the wafer gradient, the gradient value of the current pixel is compared with that of adjacent pixels along the gradient direction (such as 45). If the gradient value of the current pixel is not the largest, it is suppressed to 0. Therefore, only when the gradient value of the current pixel is greater than its two adjacent pixels in the gradient direction will it be retained; otherwise, its value is set to 0, thereby removing those redundant gradient responses that have no actual edge meaning and only retaining the true edge pixels, and the edge is refined. It should be further noted that although the edges in the refined wafer image have been refined, there may be false edge noises and incomplete edge lines in the image. Therefore, double-threshold detection and edge connection are required for the refined wafer image to obtain a binary wafer edge image. The double-threshold detection is as follows: a high threshold and a low threshold are set. For each pixel in the refined wafer image, if the amplitude of the pixel is greater than the high threshold, it indicates that the pixel is a strong edge pixel and is retained; if the amplitude of the pixel is greater than the low threshold and not greater than the high threshold, it is marked as a weak edge pixel; if the amplitude of the pixel is not greater than the low threshold, the pixel is discarded. Edge connection is as follows: if there is a strong edge pixel in the 8-neighborhood of a weak edge pixel, the weak edge pixel is retained, and the weak edge pixel is connected to the strong edge pixel until the edges in the image no longer change, and then the binary wafer edge image can be obtained.

[0039] Further, feature points of the wafer edge are extracted from the binary wafer edge image. Specifically, edge point positioning is performed on the binary wafer edge image to generate initial wafer edge feature points; key point screening is performed on the initial wafer edge feature points to obtain the wafer edge feature points. As Figure 5 shown, the wafer edge feature points are presented. It should be noted that the non-zero points in the binary wafer edge image are the initial wafer edge feature points.

[0040] Further, the center of the wafer is generated based on the feature points on the edge of the wafer. Specifically, a residual function regarding the center of the wafer is defined based on the feature points on the edge of the wafer; and the center of the wafer is obtained by fitting through a fitting optimization algorithm based on the residual function. It should be noted that the residual function also includes a user-defined radius, and the fitting optimization algorithm is the least squares method or the orthogonal distance regression algorithm. Understandably, during the fitting process, when the residual value of the residual function is minimized, the obtained center is the center of the wafer.

[0041] S130. Feature points are extracted from the edge image of the base to obtain base edge feature points, and the center of the base is generated based on the edge feature points.

[0042] In this embodiment, the calculation module extracts feature points from the edge image of the base to obtain base edge feature points, as Figure 5 shown, presenting the base edge feature points. Specifically, the edge image of the base is preprocessed to obtain a processed edge image of the base; the gradient of the base is calculated for the processed edge image of the base to obtain the base gradient; non-maximum suppression processing is performed on the base gradient to obtain a refined base image; double-threshold detection and edge connection are performed on the refined base image to obtain a binary base edge image; and feature points are extracted from the binary base edge image to obtain the base edge feature points.

[0043] Further, the step of extracting feature points from the binary base edge image to obtain the base edge feature points includes: positioning edge points of the binary base edge image to generate initial base edge feature points; and screening key points from the initial base edge feature points to obtain the base edge feature points. The step of generating the center of the base based on the base edge feature points includes: defining a residual function regarding the center of the base based on the base edge feature points; and fitting the center of the base through a fitting optimization algorithm based on the residual function. It should be noted that since the process of extracting feature points from the edge image of the base to obtain base edge feature points is the same as the process of extracting feature points from the edge image of the wafer to obtain wafer edge feature points, and the steps of generating the center of the base based on the edge feature points are also the same as the steps of generating the center of the wafer based on the wafer edge feature points, for simplicity of description, they will not be elaborated here. The specific processes of preprocessing, gradient calculation, etc. involved in the process of generating the base edge feature points will not be elaborated either.

[0044] S140. Calculate the eccentricity value based on the center of the wafer and the center of the base, and transmit the eccentricity value to the robot arm so that the robot arm adjusts the wafer according to the eccentricity value to align the center of the wafer with the center of the base.

[0045] In this embodiment, after generating the center of the wafer and the center of the base, calculate the difference between the center of the wafer and the center of the base to obtain the eccentricity value, and transmit the eccentricity value to the robot arm so that the robot arm adjusts the wafer according to the eccentricity value to align the center of the wafer with the center of the base.

[0046] Figure 6 The step - flow schematic diagram of the adjustment method for wafer center alignment according to another embodiment of the present invention is shown. As Figure 6 shown, in this embodiment, the method includes steps S110 - S150. That is, in this embodiment, before step S110 of the above - mentioned embodiment, the method further includes step S150.

[0047] S150. Calibrate the multiple cameras through a large calibration board to unify the coordinates of each camera in the same coordinate system, where the large calibration board includes a plurality of small calibration boards equal in number to the cameras.

[0048] In this embodiment, the image acquisition device includes multiple cameras. By using the positional relationship between the small calibration boards and the positional relationship between the small calibration boards and the large calibration board, the internal parameters of each camera and the external parameters relative to the small calibration board are calibrated; by using the positional relationship between the small calibration boards, the coordinates of each camera are unified in the same coordinate system. After calibrating the multiple cameras, the edge pictures can be collected. It should be noted that a calibration board is a tool for calibrating optical or measurement devices (such as cameras, lidars, 3D scanners, etc.). It is usually made of a flat plate with high - precision machining, and the surface is printed with known geometric patterns (such as checkerboards, dot arrays, QR codes, etc.). Its function is to help the device establish a coordinate system, calibrate parameters, or achieve spatial alignment between multiple sensors through the precise positioning of the pattern feature points.

[0049] Please refer to Figure 7 , Figure 7 which shows a simple schematic diagram of a thin - film deposition device according to an embodiment of the present invention. The thin - film deposition device includes a chamber and a base. After a wafer is introduced into the chamber and placed on the base, the wafer is adjusted by the above - mentioned wafer center alignment adjustment device and the above - mentioned wafer center alignment adjustment method to align the center of the wafer with the center of the base.

[0050] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for adjusting the alignment of the wafer center, characterized in that Including: Obtain an edge image collected by an image acquisition device, where the edge image includes an edge image of a wafer and an edge image of a base; Extract feature points in the edge image of the wafer to obtain wafer edge feature points, and generate the center of the wafer according to the wafer edge feature points; Extract feature points in the edge image of the base to obtain base edge feature points, and generate the center of the base according to the edge feature points; Calculate an eccentricity value according to the center of the wafer and the center of the base, and transmit the eccentricity value to a manipulator, so that the manipulator adjusts the wafer according to the eccentricity value to align the center of the wafer with the center of the base.

2. The method according to claim 1, wherein The step of extracting feature points in the edge image of the wafer / base to obtain wafer / base edge feature points includes: Preprocess the edge image of the wafer / base to obtain a processed edge image of the wafer / base; Perform gradient calculation on the processed edge image of the wafer / base to obtain a wafer / base gradient; Perform non-maximum suppression processing on the wafer / base gradient to obtain a refined wafer / base image; Perform double-threshold detection and edge connection on the refined wafer / base image to obtain a binary wafer / base edge image; Extract feature points from the binary wafer / base edge image to obtain the wafer / base edge feature points.

3. The method according to claim 2, wherein The step of extracting feature points from the binary wafer / base edge image to obtain the wafer / base edge feature points includes: Locate edge points on the binary wafer / base edge image to generate initial wafer / base edge feature points; Perform key point screening on the initial wafer / base edge feature points to obtain the wafer / base edge feature points.

4. The method according to any one of claims 1 to 3, characterized in that, The step of generating the center of the wafer / base according to the wafer / base edge feature points includes: Define a residual function regarding the center of the wafer / base according to the wafer / base edge feature points; Fit the center of the wafer / base based on the residual function through a fitting optimization algorithm.

5. The method according to any one of claims 1-3, characterized in that, The image acquisition device includes a plurality of cameras. Before the step of obtaining the edge image collected by the image acquisition device, it further includes: Calibrate the plurality of cameras through a large calibration board to unify the coordinates of each camera in the same coordinate system, where the large calibration board includes a plurality of small calibration boards equal in number to the cameras.

6. The method according to claim 5, characterized in that, The step of calibrating the plurality of cameras through the large calibration board to unify the coordinates of each camera in the same coordinate system includes: Calibrate the internal parameters of each camera and the external parameters relative to the small calibration board through the positional relationship between the small calibration boards and the positional relationship between the small calibration board and the large calibration board; Utilize the positional relationship between the small calibration boards to unify the coordinates of each camera in the same coordinate system.

7. An adjustment device for wafer center alignment, characterized in that, Including: An image acquisition device, which is arranged on a cover plate; A calculation module, which is connected to the image acquisition device, and the calculation module is configured to calculate an eccentricity value based on the edge pictures acquired by the image acquisition device, wherein the edge pictures include the edge image of the wafer and the edge image of the base; A manipulator, which is connected to the calculation module, and the manipulator is configured to adjust the wafer according to the eccentricity value so that the center of the wafer is aligned with the center of the base.

8. The device according to claim 7, characterized in that, Spray holes are provided in a ring on the cover plate, and the image acquisition device includes a plurality of image acquisition modules, and the plurality of image acquisition modules are arranged at intervals at the outer ring formed by the spray holes.

9. The device according to claim 8, wherein The image acquisition module includes a camera and a light source, wherein the camera is configured to acquire the edge pictures, and the light source is configured to improve the quality of the edge pictures acquired by the camera.

10. A thin film deposition device, characterized in that, It includes a cavity and a base. After a wafer is introduced into the cavity and placed on the base, the wafer is adjusted by the wafer center alignment adjustment device according to any one of claims 7-9 and by using the wafer center alignment adjustment method according to any one of claims 1-6 so that the center of the wafer is aligned with the center of the base.

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