Wafer alignment method and system based on finding wafer right-angle edges

Abstract

The application belongs to the technical field of semiconductor, and discloses a wafer alignment method and system based on finding a right-angle edge of a wafer, which comprises the following steps: image acquisition, using an industrial camera to take an image of a wafer placed on a workbench of a dicing machine; image preprocessing; template construction; calculating a wafer posture, in the extracted wafer image, using a Hough transform algorithm to detect a straight line segment in the wafer image, determining X and Y coordinates and a rotation angle θ of the current wafer on the workbench, so as to determine the direction and position of the wafer; calculating an alignment error, aligning and verifying the position of the wafer; the present scheme directly finds and uses the right-angle edge characteristics of the wafer for alignment, reduces the image processing flow, avoids the calculation and image data processing required by the multi-scale template matching and Hough transform algorithm in the existing wafer alignment method, and reduces the data processing time; the present application solves the problem of long processing time of the existing wafer alignment method.

Description

TECHNICAL FIELD

[0001] The present scheme belongs to the technical field of semiconductors, and particularly relates to a wafer alignment method based on finding a wafer right-angle edge and a system thereof. BACKGROUND

[0002] The wafer alignment and adjustment method is to calculate the tilt angle between the wafer cutting track and the machine tool movement axis by using image processing algorithms such as image preprocessing, edge extraction and template matching of the wafer image through a machine vision system, and to control the rotation axis of the machine tool to make corresponding rotation adjustment, so as to make the wafer cutting track parallel to the direction of the machine tool movement axis, thereby improving the precision and efficiency of the scribing and cutting wafer.

[0003] Referring to the existing document (announcement) No. CN118824901A, a semiconductor wafer position detection device and a detection method are disclosed. The detection method calculates a first adjustment angle based on edge geometric features through multi-scale template matching of a first low-magnification wafer image. The weighted calculation of multi-scale features enhances the adaptability of the algorithm to image changes. The wafer position is automatically preliminarily adjusted according to the first adjustment angle. Then, a first high-magnification wafer image and a second high-magnification wafer image are obtained. An improved Hough transform algorithm is used to calculate a second adjustment angle according to the two high-magnification wafer images, to ensure more accurate detection of the semiconductor wafer position. The wafer position is automatically accurately adjusted according to the second adjustment angle.

[0004] Although the above-mentioned wafer detection method introduces multi-scale feature fusion in the correlation measure, by comprehensively considering the features of multiple scales, it can more accurately capture the subtle changes of the wafer edge. However, this method uses a two-stage detection, i.e., preliminary detection of low-magnification images and fine detection of high-magnification images. Although this method improves the accuracy of detection, it requires more image data to be collected and processed, increasing the data processing time. Furthermore, the above-mentioned method mainly relies on multi-scale template matching and improved Hough transform algorithm to detect the wafer position, but does not directly utilize the feature of the wafer right-angle edge. The positioning information of the right-angle edge and the edge vertex makes the data processing time longer. SUMMARY

[0005] The purpose of the present scheme is to provide a wafer alignment method based on finding a wafer right-angle edge to solve the problem of long processing time of the existing wafer alignment method.

[0006] In order to achieve the above-mentioned purpose, the present scheme provides a wafer alignment method based on finding a wafer right-angle edge, comprising the following steps:

[0007] Step S10: image acquisition, using an industrial camera to take an image of the wafer placed on the scribing machine workbench to obtain the image of the wafer;

[0008] Step S20: image preprocessing, performing gray scale transformation, filtering, threshold segmentation and edge extraction on the collected wafer image;

[0009] Step S30: template construction, constructing a wafer template containing the right-angle edge features of the wafer according to the known shape and size of the wafer, which is used for subsequent image comparison and error calculation;

[0010] Step S40: wafer pose calculation, detecting the straight line segments in the wafer image extracted in step S20 using the Hough transform algorithm to determine the X, Y coordinates and rotation angle θ of the current wafer on the workbench, so as to determine the direction and position of the wafer;

[0011] Step S50: alignment error calculation, comparing the wafer image determined in step S40 with the wafer template constructed in step S30, and calculating the size and direction of the alignment error in the X, Y direction and rotation angle θ through comparison analysis;

[0012] Step S60: wafer alignment, according to the wafer pose and alignment error calculated in step S50, adjusting the position and pose of the wafer on the workbench by controlling the X, Y, C-axis movement of the dicing machine, so that the wafer reaches the predetermined position and pose;

[0013] Step S70: position verification, after the wafer is aligned, the industrial camera is used again to capture the wafer image, and the newly captured image is compared with the wafer template for the second time; if the comparison result shows that there is an error and the error exceeds the preset threshold, fine tuning is performed according to the feedback information until the deviation between the actual placement position of the wafer and the wafer template is less than or equal to the preset threshold; finally, the grinding wheel dicing machine is started to cut the wafer.

[0014] Further, in step S20, the filtering process specifically includes the following steps:

[0015] Step S21: a sliding window of size N×N is used, and the size is determined according to the noise of the wafer image and the desired filtering effect;

[0016] Step S22: the top-left corner of the wafer image obtained in step S10 is taken as the starting scanning position, and the scanning direction and step size are determined according to the size and dimensions of the wafer image, and a row-by-row and column-by-column scanning method is used;

[0017] Step S23: place the sliding window at the starting scanning position of the wafer image, and ensure that the window completely covers the pixels in this area, read the gray scale values of all the pixels in the sliding window, and store them in an array;

[0018] Step S24: Sort the pixel grayscale values ​​in the array in ascending order, find the median value of the sorted array, and use it as the median value of the current scanning area. Then replace the grayscale value of the center point of the sliding window with the calculated median value.

[0019] Step S25: According to the set scanning direction and step size, move the sliding window to the next scanning position until the sliding window has traversed the entire wafer image.

[0020] Furthermore, in step S20, the threshold segmentation specifically includes the following steps:

[0021] Step S26: Traverse each pixel in the wafer image preprocessed in step S10;

[0022] Step S27: Compare the gray value of each pixel with the set threshold; if the gray value of a pixel is greater than the threshold, set it to 255 to represent a wafer feature; if the gray value of a pixel is less than or equal to the threshold, set it to 0 to represent a background area.

[0023] Step S28: After traversing the entire wafer image, the original wafer binary image containing feature information is finally obtained, where the features on the wafer are represented by white areas and the background is represented by black areas;

[0024] The edge extraction in step S20 specifically includes the following steps:

[0025] Step S29: Perform Gaussian smoothing on the wafer image and use the Sobel operator to calculate the gradient magnitude and direction of each pixel in the image to identify the edge points of the image;

[0026] Step S210: Only retain the points with the largest magnitude in the gradient direction, and remove false edges in edge detection;

[0027] Step S211: Set a high threshold and a low threshold. The high threshold is used to identify strong edges, and the low threshold is used to connect edges. Then, the high threshold is used to obtain the edge image, and the low threshold is used to connect the broken parts in the edges. Finally, a binary image containing wafer edge information is obtained.

[0028] Furthermore, the template construction in step S30 specifically includes the following steps:

[0029] Step S31: Select a standard wafer of known shape and size as a reference, and ensure that the right-angled side of the standard wafer is parallel to the direction of the dicing machine's movement axis; then use an industrial camera to photograph the standard wafer, and ensure that the image is clear and contains the complete wafer shape;

[0030] Step S32: Convert the standard wafer image from a color image to a grayscale image, and perform filtering, thresholding, and edge extraction on the grayscale image; then use a corner detection algorithm and Hough transform method to detect feature points on the edge contour of the standard wafer image. The feature points include right-angle vertices and right-angle sides. The detected feature points are marked and recorded, including the coordinate position of the feature points in the image and the wafer edge information of the image.

[0031] Step S32: Generate a standard template image of the wafer based on the extracted feature point information. The template image contains only the edge contour and feature point markers of the wafer and does not contain any background information. Then, save the generated template image and match it with the wafer image to be processed.

[0032] Further, in step S40, based on the matching result of the wafer image and the template image, the centroid coordinates of the matching area and the deviation angle from the template image are extracted, and the deviation angle is regarded as the alignment angle of the wafer; if the deviation angle is positive, it means that the wafer needs to be rotated clockwise for alignment, and if the deviation angle is negative, it means that the wafer needs to be rotated counterclockwise for alignment; step S50 specifically includes the following steps:

[0033] Step S51: Determine the ideal position of the grinding wheel cutting focus on the wafer based on the preset cutting path and cutting track width of the dicing machine;

[0034] Step S52: Drive the grinding wheel to the preset cutting position and use an industrial camera to capture the actual position of the grinding wheel cutting focus on the wafer at this time;

[0035] Step S53: Compare the ideal position with the actual position, and calculate the translation error in the X and Y directions and the rotation error around the Z axis; where the translation error is the coordinate difference between the ideal position and the actual position in the X and Y directions, and the rotation error is the angle between the actual cutting path direction and the ideal cutting path direction.

[0036] Step S54: Based on the calculated translation error and rotation error, drive the wafer to move for error compensation adjustment; for translation error, compensate by adjusting the motion parameters of the X and Y axes; for rotation error, compensate by adjusting the angle of the C axis.

[0037] Step S55: After error compensation, use an industrial camera to photograph the actual position of the grinding wheel again to verify the compensation effect; if the error between the compensated actual position and the ideal position is within the threshold range, then perform the cutting step; if the error between the compensated actual position and the ideal position is not within the threshold range, repeat the above steps until the error value is within the threshold range.

[0038] The principle and effect of this scheme are as follows: This scheme directly finds and utilizes the right-angled edge features of the wafer for alignment, reducing the image processing steps and avoiding the computation and image data processing required by multi-scale template matching and Hough transform algorithms in existing wafer alignment methods, thus reducing data processing time. At the same time, by utilizing the geometric features of the right-angled edges of the wafer image, alignment accuracy is improved, enabling the wafer to be quickly and accurately aligned to the predetermined position and orientation.

[0039] A wafer alignment system based on finding the right-angled edges of the wafer includes:

[0040] The acquisition unit is used to acquire image information of the wafer to be cut;

[0041] A drive unit is used to control the X, Y, and C axis movements of the dicing machine and to adjust the position and orientation of the wafer on the worktable.

[0042] A cutting unit, the cutting unit being used to cut wafers;

[0043] The measurement unit includes a laser emitter, which is used to measure the position of the cutting focus of the cutting unit on the wafer;

[0044] The data processing unit is used to receive and identify the image information and cutting focus of the wafer, then compare the image of the wafer with the wafer template, calculate the wafer orientation and alignment error, control the X, Y and C axis movement of the dicing machine to adjust the position of the wafer, and finally control the cutting unit to cut the wafer along the cutting focus.

[0045] The principle and effect of this solution are as follows: Image information of the wafer is acquired by the acquisition unit, and the image is recognized and processed by the data processing unit. The right-angled edge features of the wafer are extracted and compared with a preset wafer template to calculate the wafer's position and orientation error. Then, the wafer's position and orientation on the worktable are adjusted by the drive unit to ensure the wafer achieves the predetermined alignment accuracy. Finally, the laser emitter determines the cutting focal point and drives the cutting unit to complete the cutting.

[0046] Furthermore, the cutting unit includes a grinding wheel and a drive module for driving the grinding wheel. The end of the grinding wheel shaft is provided with a sleeve. The cutting unit also includes a support platform for supporting the wafer. The laser emitter is mounted on the sleeve, and the laser emitting end of the laser emitter is tilted towards the grinding wheel tool of the grinding wheel. The measuring unit also includes a laser receiver and a controller. The controller is electrically connected to the laser receiver. The laser receiver is mounted on the support platform, and the laser receiver is configured in conjunction with the laser emitter.

[0047] The principle and effect of this scheme are as follows: (1) During the cutting process of the existing grinding wheel dicing machine, the grinding wheel tool and the wafer surface generate severe friction and collision, which causes the cutting edge to wear gradually. The debris and heat generated during cutting may also damage the cutting edge and make it dull. As a result, the wafer back edge contour is not neat when cutting the wafer, causing chipping of the wafer back cutting path, and even damaging the chip. See "Research on Silicon Wafer Composite Dicing Process" (Li Yanling, Gao Aimei, Zhang Yali. Research on Silicon Wafer Composite Dicing Process [J]. Special Equipment for Electronic Industry, 2018 (268): 25-28.). Therefore, it is necessary to inspect the grinding wheel tool for defects. (2) The grinding wheel tool in this scheme uses diamond blades. The cutting process of the grinding wheel is all existing technology, and will not be described in detail here. Before cutting the wafer, the grinding wheel tool is inspected. By starting the grinding wheel tool to rotate, the laser emitter emits laser, and the laser emitting end of the laser emitter is tilted towards the grinding wheel tool, that is, the laser is tilted to irradiate the cutting edge of the grinding wheel tool. If the tool is free of defects, i.e., the cutting edge is not dull or severely worn, the laser will shine on the diamond cutting edge and refract vertically downwards. The laser signal will be received by the laser receiver, and the controller will not issue an alarm. If the tool is defective, the laser will shine at an angle onto the support platform instead of refracting vertically downwards due to the dulling of the cutting edge. The laser receiver will not receive the laser signal, and the controller will issue an alarm signal to indicate that the grinding wheel tool is damaged. (3) The laser emitter in this scheme can locate the cutting focus of the grinding wheel tool by emitting laser light, so that the grinding wheel tool cuts along the cutting focus, thereby making the cutting path more accurate and neat. At the same time, the laser emitter can also detect whether the tool is defective or worn by emitting laser light and cooperating with the laser receiver.

[0048] Furthermore, it also includes a cleaning component, which includes a conductive rod and an electrostatic generator. The conductive rod is electrically connected to the electrostatic generator and is disposed on a sleeve. The support platform is provided with a charge plate, and the charge plate carries an opposite charge to the conductive rod. The controller is electrically connected to the electrostatic generator.

[0049] The principle and effect of this scheme are as follows: (1) When the grinding wheel tool is cutting, the workpiece is separated from the groove under the action of the tool's own rotation and the cutting water. Although there is the effect of the cutting water, dust will still float in the cutting chamber. Therefore, it is necessary to remove the dust in the cutting chamber. In this scheme, the electrostatic emitter is used to charge the conductive rod. The dust generated by the tool cutting is charged under the action of the conductive rod. When the tool is detected before cutting, if the laser receiver receives the laser, the controller controls the electrostatic generator to energize the conductive rod. Otherwise, the controller controls the electrostatic generator not to energize the conductive rod. After the tool is cut, the wafer and film on the carrier are removed. Since the charge plate and the dust have opposite charges, opposite poles attract each other, thereby attracting the dust to the charge plate. (2) This scheme determines whether to energize the conductive rod when detecting the tool. If the conductive rod is energized, the dust generated after cutting will be charged and will be adsorbed by the charge plate after cutting, thus avoiding the problem of dust in the cutting chamber being difficult to recover and clean.

[0050] Furthermore, the sleeve includes a first sleeve and a second sleeve. The conductive rod and the laser emitter are both disposed on the outer wall of the second sleeve. The first sleeve is coaxially and fixedly connected to the shaft of the grinding wheel. The end faces of the first sleeve and the second sleeve are rotatably connected. A slider and a pin are slidably disposed inside the first sleeve. The slider and the pin are connected by a pull rope. The second sleeve is provided with a socket that mates with the pin.

[0051] The principle and effect of this scheme are as follows: The first sleeve rotates in sync with the grinding wheel. During the inspection of the grinding wheel tool, the rotation speed of the grinding wheel tool is controlled at a relatively high speed. The slider is subjected to a large centrifugal force and moves away from the rotation axis. The slider drives the pin to move, thereby moving the pin away from the insertion hole. The second sleeve does not rotate, so that the laser emitted by the laser emitter is always tilted and shines on the cutting edge of the cutting tool for tool inspection. After cutting is completed, the dust in the cutting chamber is removed. At this time, the rotation speed of the grinding wheel tool is reduced. The slider is subjected to a smaller centrifugal force. Driven by the pull rope, the slider and the pin are reset. The first sleeve drives the second sleeve to rotate, thereby causing the conductive rod to rotate and contact the dust in the cutting chamber, and charge the dust.

[0052] Furthermore, the support platform has a dust collection chamber, the charge plate is disposed in the dust collection chamber, the top of the support platform is provided with a support plate, and the support plate is provided with several through holes.

[0053] The principle and effect of this solution are as follows: the wafer and the adhesive film are placed on a carrier plate during dicing. After dicing, the wafer and the adhesive film are removed, the charge plate adsorbs dust, and the dust enters the dust collection chamber through the through-hole, thereby collecting the dust into the dust collection chamber. Attached Figure Description

[0054] Figure 1This is a flowchart of a wafer alignment method based on finding the right-angled edges of a wafer according to the present invention;

[0055] Figure 2 This is a schematic diagram of the structure of a wafer alignment system based on finding the right-angled edges of a wafer according to the present invention;

[0056] Figure 3 This is a schematic diagram of the structure of the measuring unit of the present invention. Figure 1 ;

[0057] Figure 4 This is a schematic diagram of the structure of the measuring unit of the present invention. Figure 2 :

[0058] Figure 5 This is a schematic diagram of the structure of the support platform of the present invention;

[0059] Figure 6 This is a schematic diagram of the structure of the driving component of the present invention.

[0060] The reference numerals in the accompanying drawings include: wafer 1, laser emitter 2, grinding wheel 3, grinding wheel cutter 31, sleeve 4, first sleeve 41, second sleeve 42, slider 43, pin 44, pull rope 45, socket 46, support platform 5, dust collection bin 51, support plate 52, laser receiver 6, cleaning assembly 7, conductive rod 71, charge plate 72, and adhesive film 8. Detailed Implementation

[0061] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0062] Please see Figure 1 A wafer alignment method based on finding the right-angled edges of the wafer includes the following steps:

[0063] Step S10: Image acquisition. Use an industrial camera to capture images of the wafer placed on the dicing machine table to obtain images of the wafer.

[0064] Step S20: Image preprocessing, performing grayscale transformation, filtering, threshold segmentation, and edge extraction on the acquired wafer image;

[0065] Step S30: Construct a template. Based on the known shape and size of the wafer, construct a wafer template containing the right-angled edge features of the wafer. The template is used for subsequent image comparison and error calculation.

[0066] Step S40: Calculate wafer orientation. In the wafer image extracted in step S20, use the Hough transform algorithm to detect straight line segments in the wafer image, determine the X and Y coordinates of the current wafer on the worktable and the rotation angle θ, so as to determine the direction and position of the wafer.

[0067] Step S50: Calculate the alignment error. Compare the wafer image determined in step S40 with the wafer template constructed in step S30. Through comparison and analysis, calculate the magnitude and direction of the alignment error of the wafer in the X and Y directions and the rotation angle θ.

[0068] Step S60: Wafer alignment and positioning. Based on the wafer orientation and existing alignment error calculated in step S50, the position and orientation of the wafer on the worktable are adjusted by controlling the X, Y, and C axis movements of the dicing machine to make the wafer reach the predetermined position and orientation.

[0069] Step S70: Verify the position. After the wafer is aligned, use an industrial camera to capture the wafer image again and compare the newly captured image with the wafer template a second time. If the comparison result shows an error and the error exceeds the preset threshold, make fine adjustments based on the feedback information until the deviation between the actual wafer placement position and the wafer template is less than or equal to the preset threshold. Finally, start the grinding wheel dicing machine to cut the wafer.

[0070] Furthermore, in step S20, the filtering process specifically includes the following steps:

[0071] Step S21: Use an N×N sliding window and determine the size based on the noise level of the wafer image and the desired filtering effect;

[0072] Step S22: Using the upper left corner of the wafer image obtained in step S10 as the starting scanning position, and determining the scanning direction and step size according to the size and dimensions of the wafer image, a row-by-row and column-by-column scanning method is adopted.

[0073] Step S23: Place the sliding window at the starting scan position of the wafer image, and ensure that the window completely covers the pixels in the area. Read the grayscale values ​​of all pixels in the sliding window and store them in an array.

[0074] Step S24: Sort the pixel grayscale values ​​in the array in ascending order, find the median value of the sorted array, and use it as the median value of the current scanning area. Then replace the grayscale value of the center point of the sliding window with the calculated median value.

[0075] Step S25: According to the set scanning direction and step size, move the sliding window to the next scanning position until the sliding window has traversed the entire wafer image.

[0076] Furthermore, in step S20, the threshold segmentation specifically includes the following steps:

[0077] Step S26: Traverse each pixel in the wafer image preprocessed in step S10;

[0078] Step S27: Compare the gray value of each pixel with the set threshold; if the gray value of a pixel is greater than the threshold, set it to 255 to represent a wafer feature; if the gray value of a pixel is less than or equal to the threshold, set it to 0 to represent a background area.

[0079] Step S28: After traversing the entire wafer image, the original wafer binary image containing feature information is finally obtained, where the features on the wafer are represented by white areas and the background is represented by black areas;

[0080] The edge extraction in step S20 specifically includes the following steps:

[0081] Step S29: Perform Gaussian smoothing on the wafer image and use the Sobel operator to calculate the gradient magnitude and direction of each pixel in the image to identify the edge points of the image;

[0082] Step S210: Only retain the points with the largest magnitude in the gradient direction, and remove false edges in edge detection;

[0083] Step S211: Set a high threshold and a low threshold. The high threshold is used to identify strong edges, and the low threshold is used to connect edges. Then, the high threshold is used to obtain the edge image, and the low threshold is used to connect the broken parts in the edges. Finally, a binary image containing wafer edge information is obtained.

[0084] Furthermore, the template construction in step S30 specifically includes the following steps:

[0085] Step S31: Select a standard wafer of known shape and size as a reference, and ensure that the right-angled side of the standard wafer is parallel to the direction of the dicing machine's movement axis; then use an industrial camera to photograph the standard wafer, and ensure that the image is clear and contains the complete wafer shape;

[0086] Step S32: Convert the standard wafer image from a color image to a grayscale image, and perform filtering, thresholding, and edge extraction on the grayscale image; then use a corner detection algorithm and Hough transform method to detect feature points on the edge contour of the standard wafer image. The feature points include right-angle vertices and right-angle sides. The detected feature points are marked and recorded, including the coordinate position of the feature points in the image and the wafer edge information of the image.

[0087] Step S32: Generate a standard template image of the wafer based on the extracted feature point information. The template image contains only the edge contour and feature point markers of the wafer and does not contain any background information. Then, save the generated template image and match it with the wafer image to be processed.

[0088] Further, in step S40, based on the matching result of the wafer image and the template image, the centroid coordinates of the matching area and the deviation angle from the template image are extracted, and the deviation angle is regarded as the alignment angle of the wafer; if the deviation angle is positive, it means that the wafer needs to be rotated clockwise for alignment, and if the deviation angle is negative, it means that the wafer needs to be rotated counterclockwise for alignment; step S50 specifically includes the following steps:

[0089] Step S51: Determine the ideal position of the grinding wheel cutting focus on the wafer based on the preset cutting path and cutting track width of the dicing machine;

[0090] Step S52: Drive the grinding wheel to the preset cutting position and use an industrial camera to capture the actual position of the grinding wheel cutting focus on the wafer at this time;

[0091] Step S53: Compare the ideal position with the actual position, and calculate the translation error in the X and Y directions and the rotation error around the Z axis; where the translation error is the coordinate difference between the ideal position and the actual position in the X and Y directions, and the rotation error is the angle between the actual cutting path direction and the ideal cutting path direction.

[0092] Step S54: Based on the calculated translation error and rotation error, drive the wafer to move for error compensation adjustment; for translation error, compensate by adjusting the motion parameters of the X and Y axes; for rotation error, compensate by adjusting the angle of the C axis.

[0093] Step S55: After error compensation, use an industrial camera to photograph the actual position of the grinding wheel again to verify the compensation effect; if the error between the compensated actual position and the ideal position is within the threshold range, then perform the cutting step; if the error between the compensated actual position and the ideal position is not within the threshold range, repeat the above steps until the error value is within the threshold range.

[0094] To better realize the wafer alignment method based on finding the right-angled edges of the wafer, the present invention also provides a wafer alignment system based on finding the right-angled edges of the wafer.

[0095] Please see Figure 2A wafer alignment system based on finding the right-angled edges of a wafer includes an acquisition unit, a driving unit, a dicing unit, a measurement unit, and a data processing unit. The acquisition unit acquires image information of the wafer 1 to be diced; the driving unit controls the X, Y, and C-axis movements of the dicing machine and adjusts the position and orientation of the wafer 1 on the worktable; the dicing unit dices the wafer 1; the measurement unit includes a laser emitter 2, which measures the position of the dicing focus on the wafer 1; the data processing unit receives and identifies the image information and dicing focus of the wafer 1, compares the image of the wafer 1 with a wafer template, calculates the wafer orientation and alignment error, controls the X, Y, and C-axis movements of the dicing machine to adjust the position of the wafer 1, and finally controls the dicing unit to dice the wafer 1 along the dicing focus. By acquiring image information of the wafer 1 through the acquisition unit and processing the image through the data processing unit, the position and orientation errors of the wafer 1 are calculated by extracting the right-angled edge features of the wafer 1 and comparing them with a preset wafer template. Then, the position and orientation of wafer 1 on the worktable are adjusted by the drive unit to ensure that wafer 1 achieves the predetermined alignment accuracy. Finally, the laser emitter 2 determines the cutting focal point position and drives the cutting unit to complete the cutting.

[0096] Please see Figures 2-4 The cutting unit includes a grinding wheel 3 and a drive module for driving the grinding wheel 3. The end of the grinding wheel 3's rotating shaft is provided with a sleeve 4. The cutting unit also includes a support platform 5 for supporting the wafer 1. The laser emitter 2 is mounted on the sleeve 4, and the laser emitting end of the laser emitter 2 is tilted towards the grinding wheel tool 31 of the grinding wheel 3. The grinding wheel tool 31 is made of diamond. The measuring unit also includes a laser receiver 6 and a controller. The controller is electrically connected to the laser receiver 6. The laser receiver 6 is mounted on the support platform 5 and is configured in conjunction with the laser emitter 2.

[0097] Specific working principle: Before cutting wafer 1, the grinding wheel tool 31 is inspected. By starting the rotation of the grinding wheel tool 31, the laser emitter 2 emits a laser, and the laser emitting end of the laser emitter 2 is tilted towards the grinding wheel tool 31 of the grinding wheel 3, that is, the laser shines obliquely onto the cutting edge of the grinding wheel tool 31. If the tool is free of defects, that is, the cutting edge is not dulled or severely worn, the laser will shine on the diamond cutting edge and refract vertically downwards, and the laser signal will be received by the laser receiver 6, and the controller will not issue an alarm. If the tool is defective, due to the dulling of the cutting edge, the laser will shine obliquely onto the support platform 5 instead of refracting vertically downwards, and the laser receiver 6 will not receive the laser signal, then the controller will issue an alarm signal, indicating that the grinding wheel tool 31 is damaged.

[0098] Please see Figures 2-5It also includes a cleaning component 7, which includes a conductive rod 71 and an electrostatic generator. The conductive rod 71 is electrically connected to the electrostatic generator and is mounted on the sleeve 4. The support platform 5 is provided with a charge plate 72, which carries an opposite charge to the conductive rod 71. The controller is electrically connected to the electrostatic generator. The support platform 5 has a dust collection bin 51, and the charge plate 72 is located inside the dust collection bin 51. The top of the support platform 5 is provided with a support plate 52, which has several through holes.

[0099] Specific working principle: The electrostatic emitter is used to charge the conductive rod 71. The dust generated by the grinding wheel tool 31 during cutting is charged by the conductive rod 71. When the tool is detected before cutting, if the laser receiver 6 receives a laser, the controller controls the electrostatic generator to energize the conductive rod 71; otherwise, it controls the electrostatic generator not to energize the conductive rod 71. After the tool is cut, the wafer 1 and the adhesive film 8 are removed from the support stage. Since the charge plate 72 and the dust have opposite charges, opposite poles attract each other, thus attracting the dust to the charge plate 72 and into the dust collection chamber 51 through the through hole, thereby collecting the dust in the dust collection chamber 51.

[0100] Please see Figure 6 The sleeve 4 includes a first sleeve 41 and a second sleeve 42. The conductive rod 71 and the laser emitter 6 are both disposed on the outer wall of the second sleeve 42. The first sleeve 41 is coaxially fixedly connected to the rotating shaft of the grinding wheel 3. The end faces of the first sleeve 41 and the second sleeve 42 are rotatably connected. The first sleeve 41 is slidably provided with a slider 43 and a pin 44. The slider 43 and the pin 44 are connected by a pull rope 45. The second sleeve 42 is provided with a socket 46 that mates with the pin 44.

[0101] Specific working principle: The first sleeve 41 rotates in sync with the grinding wheel 3. When inspecting the grinding wheel tool 31, the rotation speed of the grinding wheel tool 31 is controlled to be relatively high. The slider 43 is subjected to a large centrifugal force and moves away from the rotation axis. The slider 43 drives the pin 44 to move, thereby moving the pin 44 away from the insertion hole 46. The second sleeve 42 does not rotate, so that the laser emitted by the laser emitter 2 always shines obliquely onto the cutting edge of the cutting tool for tool inspection. After cutting, the cutting chamber is cleaned. At this time, the rotation speed of the grinding wheel tool 31 is reduced. The slider 43 is subjected to a smaller centrifugal force. Driven by the pull rope 45, the slider 43 and the pin 44 are reset. The first sleeve 41 drives the second sleeve 42 to rotate, thereby causing the conductive rod 71 to rotate and contact the dust in the cutting chamber, and to charge the dust.

[0102] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A wafer alignment method based on finding the right-angled edges of a wafer, characterized in that, Includes the following steps: Step S10: Image acquisition. Use an industrial camera to capture images of the wafer placed on the dicing machine table to obtain images of the wafer. Step S20: Image preprocessing, performing grayscale transformation, filtering, threshold segmentation, and edge extraction on the acquired wafer image; Step S30: Construct a template. Based on the known shape and size of the wafer, construct a wafer template containing the right-angled edge features of the wafer. The template is used for subsequent image comparison and error calculation. Step S40: Calculate wafer orientation. In the wafer image extracted in step S20, use the Hough transform algorithm to detect straight line segments in the wafer image, determine the X and Y coordinates of the current wafer on the worktable and the rotation angle θ, so as to determine the direction and position of the wafer. Step S50: Calculate the alignment error. Compare the wafer image determined in step S40 with the wafer template constructed in step S30. Through comparison and analysis, calculate the magnitude and direction of the alignment error of the wafer in the X and Y directions and the rotation angle θ. Step S60: Wafer alignment and positioning. Based on the wafer orientation and existing alignment error calculated in step S50, the position and orientation of the wafer on the worktable are adjusted by controlling the X, Y, and C axis movements of the dicing machine to make the wafer reach the predetermined position and orientation. Step S70: Verify the position. After the wafer is aligned, use an industrial camera to capture the wafer image again and compare the newly captured image with the wafer template a second time. If the comparison result shows an error and the error exceeds the preset threshold, make fine adjustments based on the feedback information until the deviation between the actual wafer placement position and the wafer template is less than or equal to the preset threshold. Finally, the dicing machine is started to cut the wafer.

2. The wafer alignment method based on finding the right-angled edges of the wafer according to claim 1, characterized in that: In step S20, the filtering process specifically includes the following steps: Step S21: Use an N×N sliding window and determine the size based on the noise level of the wafer image and the desired filtering effect; Step S22: Using the upper left corner of the wafer image obtained in step S10 as the starting scanning position, and determining the scanning direction and step size according to the size and dimensions of the wafer image, a row-by-row and column-by-column scanning method is adopted. Step S23: Place the sliding window at the starting scan position of the wafer image, and ensure that the window completely covers the pixels at that position. Read the grayscale values ​​of all pixels within the sliding window and store them in an array. Step S24: Sort the pixel grayscale values ​​in the array in ascending order, find the median value of the sorted array, and use it as the median value of the current scanning area. Then replace the grayscale value of the center point of the sliding window with the calculated median value. Step S25: According to the set scanning direction and step size, move the sliding window to the next scanning position until the sliding window has traversed the entire wafer image.

3. The wafer alignment method based on finding the right-angled edges of the wafer according to claim 1, characterized in that: In step S20, threshold segmentation specifically includes the following steps: Step S26: Traverse each pixel in the wafer image preprocessed in step S10; Step S27: Compare the gray value of each pixel with the set threshold; if the gray value of a pixel is greater than the threshold, set it to 255 to represent a wafer feature; if the gray value of a pixel is less than or equal to the threshold, set it to 0 to represent a background area. Step S28: After traversing the entire wafer image, the original wafer binary image containing feature information is finally obtained, where the features on the wafer are represented by white areas and the background is represented by black areas; The edge extraction in step S20 specifically includes the following steps: Step S29: Perform Gaussian smoothing on the wafer image and use the Sobel operator to calculate the gradient magnitude and direction of each pixel in the image to identify the edge points of the image; Step S210: Only retain the points with the largest magnitude in the gradient direction, and remove false edges in edge detection; Step S211: Set a high threshold and a low threshold. The high threshold is used to identify strong edges, and the low threshold is used to connect edges. Then, the high threshold is used to obtain the edge image, and the low threshold is used to connect the broken parts in the edges. Finally, a binary image containing wafer edge information is obtained.

4. The wafer alignment method based on finding the right-angled edges of a wafer according to claim 1, characterized in that: The process of constructing the template in step S30 specifically includes the following steps: Step S31: Select a standard wafer of known shape and size as a reference, and ensure that the right-angled side of the standard wafer is parallel to the direction of the dicing machine's movement axis; then use an industrial camera to photograph the standard wafer, and ensure that the image is clear and contains the complete wafer shape; Step S32: Convert the standard wafer image from a color image to a grayscale image, and perform filtering, thresholding, and edge extraction on the grayscale image; then use a corner detection algorithm and Hough transform method to detect feature points on the edge contour of the standard wafer image. The feature points include right-angle vertices and right-angle sides. The detected feature points are marked and recorded, including the coordinate position of the feature points in the image and the wafer edge information of the image. Step S32: Generate a standard template image of the wafer based on the extracted feature point information. The template image contains only the edge contour and feature point markers of the wafer and does not contain any background information. Then, save the generated template image and match it with the wafer image to be processed.

5. The wafer alignment method based on finding the right-angled edges of the wafer according to claim 1, characterized in that: In step S40, based on the matching result between the wafer image and the template image, the centroid coordinates of the matching region and the deviation angle from the template image are extracted, and the deviation angle is regarded as the alignment angle of the wafer; if the deviation angle is positive, it means that the wafer needs to be rotated clockwise for alignment, and if the deviation angle is negative, it means that the wafer needs to be rotated counterclockwise for alignment; step S50 specifically includes the following steps: Step S51: Determine the ideal position of the grinding wheel cutting focus on the wafer based on the preset cutting path and cutting track width of the dicing machine; Step S52: Drive the grinding wheel to the preset cutting position and use an industrial camera to capture the actual position of the grinding wheel cutting focus on the wafer at this time; Step S53: Compare the ideal position with the actual position, and calculate the translation error in the X and Y directions and the rotation error around the Z axis; where the translation error is the coordinate difference between the ideal position and the actual position in the X and Y directions, and the rotation error is the angle between the actual cutting path direction and the ideal cutting path direction. Step S54: Based on the calculated translation error and rotation error, drive the wafer to move for error compensation adjustment; for translation error, compensate by adjusting the motion parameters of the X and Y axes; for rotation error, compensate by adjusting the angle of the C axis. Step S55: After error compensation, use an industrial camera again to photograph the actual position of the grinding wheel to verify the compensation effect; If the error between the compensated actual position and the ideal position is within the threshold range, then the cutting step is performed; If the error between the compensated actual position and the ideal position is not within the threshold range, repeat the above steps until the error value is within the threshold range.

6. A wafer alignment system based on finding the right-angled edges of a wafer, comprising applying a wafer alignment method based on finding the right-angled edges of a wafer as described in any one of claims 1-5, characterized in that, include: The acquisition unit is used to acquire image information of the wafer (1) to be cut; A drive unit is used to control the X, Y, and C axis movements of the dicing machine and to adjust the position and orientation of the wafer (1) on the worktable. A cutting unit, the cutting unit being used to cut a wafer (1); The measurement unit includes a laser emitter (2) for measuring the position of the cutting focus of the cutting unit on the wafer (1); The data processing unit is used to receive and identify the image information and cutting focus of the wafer (1), then compare the image of the wafer (1) with the wafer template, calculate the wafer orientation and alignment error, control the X, Y and C axis movement of the dicing machine, adjust the position of the wafer (1), and finally control the cutting unit to cut the wafer (1) along the cutting focus.

7. A wafer alignment system based on finding the right-angled edges of a wafer according to claim 6, characterized in that: The cutting unit includes a grinding wheel (3) and a drive module for driving the grinding wheel (3). The end of the shaft of the grinding wheel (3) is provided with a sleeve (4). The cutting unit also includes a support platform (5) for carrying the wafer (1). The laser emitter (2) is located on the sleeve (4), and the laser emitting end of the laser emitter (2) is tilted towards the grinding wheel tool (31) of the grinding wheel (3). The measuring unit also includes a laser receiver (6) and a controller. The controller is electrically connected to the laser receiver (6). The laser receiver (6) is located on the support platform (5). The laser receiver (6) is configured in conjunction with the laser emitter (2).

8. A wafer alignment system based on finding the right-angled edges of a wafer according to claim 7, characterized in that: It also includes a cleaning component (7), which includes a conductive rod (71) and an electrostatic generator. The conductive rod (71) is electrically connected to the electrostatic generator. The conductive rod (71) is mounted on a sleeve (4). The support platform (5) is provided with a charge plate (72). The charge plate (72) carries a charge opposite to that of the conductive rod (71). The controller is electrically connected to the electrostatic generator.

9. A wafer alignment system based on finding the right-angled edges of a wafer according to claim 8, characterized in that: The sleeve (4) includes a first sleeve (41) and a second sleeve (42). The conductive rod (71) and the laser emitter (2) are both located on the outer wall of the second sleeve (42). The first sleeve (41) is coaxially fixedly connected to the shaft of the grinding wheel (3). The end faces of the first sleeve (41) and the second sleeve (42) are rotatably connected. A slider (43) and a pin (44) are slidably provided inside the first sleeve (41). The slider (43) and the pin (44) are connected by a pull rope (45). The second sleeve (42) is provided with a socket (46) that cooperates with the pin (44).

10. A wafer alignment system based on finding the right-angled edges of a wafer according to claim 9, characterized in that: The support platform (5) has a dust collection chamber (51), the charge plate (72) is located in the dust collection chamber (51), the top of the support platform (5) is provided with a support plate (52), and the support plate (52) is provided with several through holes.

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