Wafer pre-alignment method and related apparatus

Abstract

Embodiments of the present application disclose a wafer pre-alignment method and related equipment, which can acquire an image of a wafer to be aligned; a positioning area is segmented from the image, the positioning area containing a positioning slot with a symmetrical geometric shape in the wafer to be aligned; a bounding box of the positioning area is rotated multiple times, and a sub-area is extracted from the rotated positioning area to obtain multiple candidate sub-areas containing a slot reference line, the slot reference line including a connecting line between two end points where the positioning slot meets an outer contour of the wafer to be aligned; a symmetry score of the candidate sub-area is calculated, and based on the symmetry score, a target sub-area is selected from the multiple candidate sub-areas; according to the gray distribution information of the target sub-area, point position information of a midpoint of the slot reference line is determined; and the control unit is triggered to perform wafer alignment based on the angle information, the area position information and the point position information of the target sub-area, so as to improve the wafer pre-alignment efficiency.

Description

Technical Field

[0001] This application relates to the semiconductor field, specifically to a wafer pre-alignment method and related equipment. Background Technology

[0002] In semiconductor manufacturing, precise wafer alignment is a critical prerequisite for ensuring the successful implementation of the process. Alignment typically involves multiple rounds with progressively increasing precision, with each round laying the foundation for the next. Wafer pre-alignment, as one of the earlier alignment rounds, needs to pursue higher efficiency while meeting certain precision requirements. There are two main approaches to this: one is to use sensors to sense the wafer edge and identify lateral, longitudinal, and angular offsets, but this approach has relatively low efficiency and accuracy. The other approach involves capturing an image of the wafer on its carrier surface and fitting it to the wafer edge contour to obtain the current center. The current angle is then determined by identifying the positioning groove contour and compared with a reference center and reference angle to determine the lateral, longitudinal, and angular offsets. However, identifying the center and angle of the wafer image is implemented using different algorithms, which is cumbersome and consumes significant computational resources and time. Summary of the Invention

[0003] This application provides a wafer pre-alignment method and related equipment, which can improve wafer pre-alignment efficiency.

[0004] This application discloses a wafer pre-alignment method, including:

[0005] Acquire an image of the wafer to be aligned;

[0006] The positioning region is segmented from the image, and the positioning region contains positioning grooves with symmetrical geometry in the wafer to be aligned;

[0007] The bounding box of the positioning area is rotated multiple times, and sub-regions are extracted from the rotated positioning area to obtain multiple candidate sub-regions containing slot reference lines, as well as the angle information and region position information of each candidate sub-region. The slot reference line includes the line connecting the two endpoints of the positioning slot and the outer contour of the wafer to be aligned.

[0008] Calculate the symmetry score of the candidate sub-regions, and filter the target sub-regions from multiple candidate sub-regions based on the symmetry score;

[0009] Based on the grayscale distribution information of the target sub-region, determine the point position information of the midpoint of the slot reference line;

[0010] The trigger control unit adjusts the position of the wafer to be aligned on the wafer carrier surface based on the angle information, region position information and point position information of the target sub-region, so as to achieve wafer alignment.

[0011] This application discloses a wafer pre-alignment apparatus, comprising:

[0012] The acquisition module is used to acquire images of the wafer to be aligned;

[0013] The segmentation module is used to segment the positioning region from the image, the positioning region containing positioning grooves with symmetrical geometry in the wafer to be aligned;

[0014] The candidate module is used to rotate the bounding box of the positioning area multiple times and extract sub-regions from the rotated positioning area to obtain multiple candidate sub-regions containing slot reference lines, as well as the angle information and region position information of each candidate sub-region. The slot reference line includes the line connecting the two endpoints of the positioning slot and the outer contour of the wafer to be aligned.

[0015] The calculation module is used to calculate the symmetry score of the candidate sub-regions and filter the target sub-regions from multiple candidate sub-regions based on the symmetry score;

[0016] The determination module is used to determine the point position information of the midpoint of the slot reference line based on the grayscale distribution information of the target sub-region;

[0017] The alignment module is used to trigger the control unit to adjust the position of the wafer to be aligned on the wafer carrier surface based on the angle information, region position information and point position information of the target sub-region, so as to achieve wafer alignment.

[0018] In some embodiments of this application, the calculation module is specifically used for:

[0019] The candidate sub-regions are divided into multiple sub-regions with equal width. Based on the average gray value of the multiple sub-regions, a gray value curve is generated. Starting from the midpoint of the gray value curve, the minimum value points corresponding to the minimum values ​​on the left and right sides that are less than the first preset threshold are found respectively to obtain the left endpoint and the right endpoint.

[0020] Based on the left and right endpoints, calculate the first symmetry score, the second symmetry score, and the edge gradient score of the candidate sub-region;

[0021] Based on preset fusion weights, the first symmetry score, the second symmetry score, and the edge gradient score are fused to obtain the symmetry score of the candidate sub-region.

[0022] In some embodiments of this application, the calculation module is specifically used for:

[0023] Within the candidate sub-regions, the sub-region corresponding to the left endpoint is determined as the left endpoint region, and the sub-region corresponding to the right endpoint is determined as the right endpoint region.

[0024] The left and right endpoint regions are processed based on a first preset strategy in the first direction indicated by the angular information of the positioning area to calculate the first symmetry score of the candidate sub-regions;

[0025] The left and right endpoint regions are processed in the second direction based on the second preset strategy to calculate the second symmetry score and edge gradient score of the candidate sub-region. The first and second directions are perpendicular to each other.

[0026] In some embodiments of this application, the calculation module is specifically used for:

[0027] Starting from the left endpoint region, the left endpoint region is moved within a preset range along the first direction indicated by the angle information of the positioning region according to the first preset step size, and the average gray value of each left endpoint region is calculated to obtain the first left gray value change function.

[0028] Starting from the right endpoint region, move the right endpoint region within a preset range in the opposite direction of the first direction according to the first preset step size, and calculate the average gray value of each right endpoint region to obtain the first right gray value change function.

[0029] The first symmetry score is obtained by subtracting the gray value change function on the left side and the gray value change function on the right side.

[0030] In some embodiments of this application, the calculation module is specifically used for:

[0031] Starting from the left endpoint region, move the left endpoint region along the second direction within a preset range according to the second preset step size, and calculate the average gray value of each left endpoint region to obtain the second left gray value change function;

[0032] Starting from the right endpoint region, the right endpoint region is moved within a preset range along the second direction with a second preset step size, and the average gray value of each right endpoint region is calculated to obtain the second right gray value change function.

[0033] The second symmetry score is obtained by subtracting the second left-side grayscale value change function from the second right-side grayscale value change function.

[0034] The edge gradient score of the candidate sub-region is calculated based on the second left gray value change function and the second right gray value change function.

[0035] In some embodiments of this application, the calculation module is specifically used for:

[0036] Calculate the first derivatives of the second left-side grayscale value change function and the second right-side grayscale value change function respectively to obtain the left-side gradient change function and the right-side gradient change function;

[0037] The average values ​​of the gradient change functions on the left and right sides are calculated separately, and the two average values ​​are combined to obtain the edge gradient score of the candidate sub-region.

[0038] In some embodiments of this application, the determining module is specifically used for:

[0039] Calculate the gradient curve of the vertical projection of the target sub-region;

[0040] Determine the coordinate range of the midpoint of the slot reference line in the target sub-region, and select multiple candidate point coordinates in the coordinate range of the gradient curve;

[0041] Calculate the score for each candidate point coordinate, and based on the ranking of multiple scores, filter out the target point coordinates from multiple candidate point coordinates, and determine the point position information of the midpoint of the slot reference line as the target point coordinates.

[0042] In some embodiments of this application, the determining module is specifically used for:

[0043] Starting from the midpoint coordinates of the gradient curve, determine the left and right endpoints of the target on both sides of the midpoint coordinates;

[0044] Based on the left and right endpoints of the target, determine the coordinate range of the curve segment to be extracted, and determine the initial point coordinates of the midpoint of the coordinate range as the midpoint of the slot reference line.

[0045] Based on the initial point coordinates and the preset interval length, determine the coordinate interval of the midpoint of the slot reference line in the target sub-region.

[0046] In some embodiments of this application, the determining module is specifically used for:

[0047] In the coordinate system of the gradient curve, starting from the coordinates of the candidate point, select the first curve segment and the second curve segment with the same interval length along the positive and negative x-axis, respectively.

[0048] The similarity between the first curve segment and the second curve segment is evaluated to obtain the score of the candidate point coordinates.

[0049] In some embodiments of this application, the determining module is specifically used for:

[0050] Starting from the midpoint coordinates of the gradient curve, find the extreme points corresponding to the extreme values ​​at both ends that match the second preset threshold, and obtain the initial left endpoint and the initial right endpoint.

[0051] Starting from the initial left endpoint, search along the positive direction on the gradient curve for the first maximum value that is greater than the third preset threshold, and determine the maximum value point as the target left endpoint.

[0052] Starting from the initial right endpoint, search along the negative direction on the gradient curve for the first minimum value that is greater than the fourth preset threshold, and determine the minimum point as the target right endpoint.

[0053] In some embodiments of this application, the segmentation module is specifically used for:

[0054] Calculate the horizontal projection curve of the image, and obtain the first maximum point and the second minimum point in the horizontal projection curve;

[0055] Based on the maximum and minimum points and the preset coordinate range, the region containing the positioning slot is segmented from the image.

[0056] In some embodiments of this application, the candidate module is specifically used for:

[0057] Within a first preset angle range, the bounding box of the positioning area is rotated multiple times with a first preset angle step size to obtain multiple rotated positioning areas and their respective angle information.

[0058] Along a second direction perpendicular to the first direction indicated by the angular information of the positioning area, the rotated positioning area is divided into multiple sub-regions and their respective regional position information by a first preset height step.

[0059] Candidate sub-regions containing the slot reference line are filtered from multiple sub-regions to obtain the candidate sub-regions of each of the multiple rotated positioning regions, as well as the angle information and region position information of the candidate sub-regions.

[0060] In some embodiments of this application, the candidate module is specifically used for:

[0061] Based on the average gray value of the sub-region, the average gray value curve of the rotated positioning region is determined, and the first derivative of the average gray value curve is obtained to get the average gray value gradient curve.

[0062] Find the minimum point in the average gray-scale gradient curve where the absolute value of the minimum value is greater than the fifth preset threshold, and determine the sub-region corresponding to the minimum point as a candidate sub-region.

[0063] In some embodiments of this application, the calculation module is specifically used for:

[0064] The symmetry scores are sorted, and the target sub-region is selected from multiple candidate sub-regions based on the sorting results.

[0065] In some embodiments of this application, the calculation module is specifically used for:

[0066] The candidate sub-regions corresponding to symmetry scores greater than the set ranking are identified as the middle sub-regions;

[0067] Within the second preset angle range, the intermediate sub-region is rotated multiple times with a second preset angle step size to obtain multiple rotated intermediate sub-regions and their respective angle information. The second preset angle range is smaller than the first preset angle range, and the second preset angle step size is smaller than the first preset angle step size.

[0068] The rotated middle sub-region is divided in the second direction with a second preset height step size to obtain multiple subdivided regions and their respective region position information. The second preset height step size is smaller than the first preset height step size.

[0069] Candidate subdivision regions containing the slot reference line are filtered from multiple subdivision regions to obtain the candidate subdivision regions for each of the multiple rotated intermediate sub-regions, as well as the angle information and region position information of the candidate subdivision regions;

[0070] Calculate the symmetry score of the candidate sub-regions, and select the target sub-region from multiple candidate sub-regions based on the symmetry score.

[0071] In some embodiments of this application, the alignment module is specifically used to: determine the angular deflection of the wafer to be aligned relative to the wafer reference orientation on the wafer carrier surface based on angle information;

[0072] Based on the region location and the point location information, the lateral offset and longitudinal offset of the wafer to be aligned relative to the wafer reference position on the wafer bearing surface are determined;

[0073] The control is triggered to adjust the position of the wafer to be aligned on the wafer carrier surface based on the angle deflection, the lateral offset, and the longitudinal offset, so as to achieve wafer alignment.

[0074] In some embodiments of this application, the alignment module is specifically used for:

[0075] Based on the region location and the point location information, determine the current position of the midpoint of the slot reference line on the wafer to be aligned;

[0076] Based on the current position and the reference position of the midpoint of the wafer slot reference line on the wafer carrier surface, the lateral offset and longitudinal offset of the wafer to be aligned are calculated.

[0077] Accordingly, this application also provides a computer device, including a processor and a memory, wherein the memory stores a computer program, and the processor is used to run the computer program in the memory to implement the steps in the wafer pre-alignment method provided in this application.

[0078] Accordingly, embodiments of this application also provide a computer-readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the steps in the wafer pre-alignment method provided in embodiments of this application.

[0079] Accordingly, embodiments of this application also provide a computer program product, including a computer program or instructions, which are executed by a processor to implement the steps in the wafer pre-alignment method provided in embodiments of this application.

[0080] This application embodiment can acquire an image of the wafer to be aligned, segment a positioning region from the image, the positioning region includes a positioning groove with a symmetrical geometric shape in the wafer to be aligned, then rotate the bounding box of the positioning region multiple times in micro-angle increments, and extract sub-regions from the rotated positioning region to obtain multiple candidate sub-regions containing a slot reference line, as well as angle information and region position information of each candidate sub-region. The slot reference line includes the line connecting the two endpoints of the positioning groove and the outer contour of the wafer to be aligned. Then, the symmetry score of the candidate sub-regions is calculated, and based on the symmetry score, a target sub-region is selected from multiple candidate sub-regions. According to the grayscale distribution information of the target sub-region, the point position information of the midpoint of the slot reference line is determined. Finally, the control unit is triggered to adjust the position of the wafer to be aligned on the wafer carrier surface based on the angle information, region position information, and point position information of the target sub-region to achieve wafer alignment.

[0081] The wafer to be aligned is usually initially placed in a certain location, and images are acquired through an acquisition device. At this time, the position of the wafer to be aligned is usually offset from the ideal position, that is, the position of the positioning slot is offset. Since the geometry of the positioning slot is symmetrical, this application, based on this, through steps such as rotating the positioning area and evaluating the symmetry of the sub-region, can determine the angle information of the target sub-region as the angle offset information of the positioning slot without identifying the positioning slot and the wafer edge contour. Further identification of the target sub-region yields the point position information of the midpoint of the positioning slot opening reference line. Wafer pre-alignment can be achieved directly through the difference between the midpoint position and the ideal midpoint position, as well as the angle deflection information, significantly improving the pre-alignment efficiency. Attached Figure Description

[0082] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0083] Figure 1 This is a schematic flowchart of the wafer pre-alignment method provided in an embodiment of this application;

[0084] Figure 2 This is a schematic diagram of the positioning groove in the wafer pre-alignment method provided in the embodiments of this application;

[0085] Figure 3This is a schematic diagram of another positioning groove in the wafer pre-alignment method provided in the embodiments of this application;

[0086] Figure 4 This is a schematic diagram of another positioning groove in the wafer pre-alignment method provided in the embodiments of this application;

[0087] Figure 5 This is a schematic diagram of the wafer pre-alignment method provided in the embodiments of this application;

[0088] Figure 6 This is a schematic diagram of another positioning groove in the wafer pre-alignment method provided in the embodiments of this application;

[0089] Figure 7 This is another schematic diagram of the wafer pre-alignment method provided in the embodiments of this application;

[0090] Figure 8 This is another schematic diagram of the wafer pre-alignment method provided in the embodiments of this application;

[0091] Figure 9 This is a schematic diagram of another positioning groove in the wafer pre-alignment method provided in the embodiments of this application;

[0092] Figure 10 This is a schematic diagram of the pre-alignment of the wafer pre-alignment method provided in the embodiments of this application;

[0093] Figure 11 This is a schematic diagram of the structure of the computer device provided in the embodiments of this application. Detailed Implementation

[0094] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0095] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0096] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0097] In the embodiments of this application, the terms "module" or "unit" refer to a computer program or part of a computer program that has a predetermined function and works with other related parts to achieve a predetermined goal, and can be implemented wholly or partially using software, hardware (such as processing circuitry or memory), or a combination thereof. Similarly, a processor (or multiple processors or memory) can be used to implement one or more modules or units. Furthermore, each module or unit can be part of an overall module or unit that includes the functionality of that module or unit.

[0098] This application discloses a wafer pre-alignment method and related equipment. The wafer pre-alignment method includes: acquiring an image of a wafer to be aligned; segmenting a positioning region from the image, the positioning region containing a positioning groove with a symmetrical geometric shape in the wafer to be aligned; rotating the bounding box of the positioning region multiple times, and extracting sub-regions from the rotated positioning region to obtain multiple candidate sub-regions containing a slot reference line, as well as angle information and region position information of each candidate sub-region, the slot reference line including the line connecting the two endpoints of the positioning groove and the outer contour of the wafer to be aligned; calculating the symmetry score of the candidate sub-regions, and selecting a target sub-region from the multiple candidate sub-regions based on the symmetry score; determining the point position information of the midpoint of the slot reference line in the target sub-region according to the grayscale distribution information of the target sub-region; and triggering a control unit to adjust the position of the wafer to be aligned on the wafer carrier surface based on the angle information, region position information, and point position information of the target sub-region to achieve wafer alignment.

[0099] In this embodiment, the wafer pre-alignment method can be applied to a wafer pre-alignment device.

[0100] Wafer pre-alignment devices can be installed in semiconductor equipment used in semiconductor manufacturing, such as metrology equipment, process equipment, and handling equipment / systems. Process equipment includes manufacturing execution units at various stages of the semiconductor industry chain that alter the shape, structure, composition, or properties of the processed object through physical or chemical processes to achieve specific functional layers or structures, such as thin film deposition equipment, photolithography equipment, etching equipment, dicing equipment, and bonding equipment. Metrology equipment includes precision instrument systems used throughout the entire semiconductor process for non-destructive measurement, identification, and data analysis of the geometric features, physical properties, and defect states of the processed object, such as film thickness measurement equipment, critical dimension measurement equipment, defect detection equipment, and overlay error measurement equipment.

[0101] Wafer pre-alignment devices can also be applied to virtual systems such as digital twin systems and simulation systems.

[0102] The wafer pre-alignment apparatus can be integrated into at least one computer device, and multiple computer devices can be networked together via wired or wireless means. The computer devices can be, for example, terminals or servers. Terminal device types include, but are not limited to, at least one of: smartphones, tablets, personal computers (PCs), laptops, and desktop computers. Those skilled in the art will understand that the number of terminals can be more or less. This application does not limit the number or type of terminals.

[0103] A server can be a standalone physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides cloud computing services such as cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, content delivery networks (CDN), and basic cloud computing services such as big data and artificial intelligence platforms.

[0104] Taking the wafer pre-alignment device integrated into the mass inspection equipment as an example, the mass inspection equipment also includes modules such as a transmission unit for carrying, transporting, and aligning the wafer, and a vision device for acquiring wafer images. The modules are connected in communication. The transmission unit transports the wafer to the wafer carrier surface, which is placed in the image acquisition area of ​​the vision device.

[0105] The wafer pre-alignment device acquires an image of the wafer to be aligned taken by an image acquisition device at a specific location. It segments a positioning region from the image, which includes positioning slots with symmetrical geometric shapes on the wafer to be aligned. The bounding box of the positioning region is rotated multiple times, and sub-regions are extracted from the rotated positioning region to obtain multiple candidate sub-regions containing slot reference lines, as well as angle and location information for each candidate sub-region. The slot reference lines include the lines connecting the two endpoints where the positioning slots meet the outer contour of the wafer to be aligned. The symmetry score of the candidate sub-regions is calculated, and a target sub-region is selected from the multiple candidate sub-regions based on the symmetry score. The position information of the midpoint of the slot reference line within the target sub-region is determined based on the grayscale distribution information of the target sub-region.

[0106] The wafer pre-alignment device can transmit angle information, region position information, and point position information of the target sub-region to the control unit. The control unit can calculate the offset information of the wafer to be aligned relative to the ideal position based on the angle information, region position information, and point position information, and send an alignment command including this offset information to the transmission unit. The transmission unit can achieve wafer alignment based on the position of the wafer to be aligned on the wafer carrier surface based on the alignment command.

[0107] It should be noted that the control unit here can be a module at the same level as the wafer pre-alignment device and the transmission unit in the quantity detection equipment, or it can be a lower-level module in the transmission unit. The specific choice can be flexibly considered according to the actual application scenario, and this application will not elaborate further on this.

[0108] It should also be noted that the wafer pre-alignment device can also directly calculate the offset information of the wafer to be aligned relative to the ideal position based on the angle information, region position information and point position information of the target sub-region, and transmit the offset information to the control unit.

[0109] The above is merely an illustrative example and does not constitute a limitation on the application scenarios of this application. The wafer pre-alignment method of this application will be further described below with reference to embodiments.

[0110] Please see Figure 1 , Figure 1 A flowchart of the wafer pre-alignment method of this application is shown. The wafer pre-alignment method may include:

[0111] Step 110: Obtain an image of the wafer to be aligned.

[0112] In this embodiment of the application, the wafer to be aligned may include a wafer that needs to be placed in an ideal position, but the current actual placement position deviates from the ideal position. An image of the wafer to be aligned can be acquired at a specific position by an image acquisition device.

[0113] There may be angular and / or positional deviations between the ideal and actual positions. For example, angular deviations can be calculated based on the current position of the positioning slot and the ideal position, while positional deviations can be calculated based on the current position and the ideal position of a point on the wafer with significantly different characteristics.

[0114] The image of the wafer to be aligned can be acquired by the image acquisition module on the process equipment. The image acquisition module can be moved to a specific position to acquire the image, or it can be set to directly acquire the image at a specific position. The image of the wafer to be aligned can include part or all of the wafer outline (but must include the positioning groove). When the image includes part of the wafer outline, it can be directly acquired by the image acquisition module, or it can be cropped from an image including the entire wafer outline; the specific approach can be flexibly handled according to the application scenario. The image to be aligned can be a grayscale image.

[0115] Step 120: Segment the positioning region from the image. The positioning region contains positioning grooves with symmetrical geometry in the wafer to be aligned.

[0116] Positioning grooves can be flat or notched, and the shape of the notch can be U-shaped or V-shaped. These shapes are all symmetrical geometric shapes. Positioning grooves can determine the crystal orientation of the marked silicon wafer and enable the wafer to be correctly positioned and aligned in semiconductor manufacturing equipment.

[0117] The positioning area may include part or all of the outline of the positioning slot, as well as the outline of other wafer regions adjacent to this part or all of the positioning slot, such as... Figure 2 An image of the wafer to be aligned is shown, with the positioning area circled in red.

[0118] There are several ways to segment the positioning area from the wafer image to be aligned. For example, you can first detect the wafer outline by edge detection, then segment the wafer outline to match a preset standard shape outline, and take the most matching part of the wafer outline as the center area to segment the positioning area from the entire wafer to be positioned. The preset standard shape outline includes part or all of the standard outline of the positioning groove.

[0119] In some embodiments of this application, taking an image that includes a portion of the wafer outline and a positioning region that includes a portion of the positioning groove outline as an example, the method for segmenting the positioning region from the image can be as follows: determine the opening orientation of the positioning groove in the image. The opening orientation can be identified, or input data or pre-stored data can be accepted. If the opening orientation does not match the preset position, the image needs to be rotated by a certain angle, such as 90°, 180°, or 270°, to correct the opening orientation of the positioning groove outline in the image to match the preset position.

[0120] Taking the preset position as the starting point and moving towards the positive Y-axis as an example, such as... Figure 2As shown, the horizontal projection curve of the image can be calculated at this time, and the first maximum point and the second minimum point in the horizontal projection curve can be obtained. Based on the maximum point, the minimum point and the preset coordinate interval, the region containing the positioning groove can be segmented from the image.

[0121] Specifically, the horizontal projection curve can evaluate the cumulative characteristics of pixels in the horizontal direction (different pixel rows). Since edge contours are mostly dark in the image of the wafer to be aligned, and non-contours are mostly light, when the positioning slot opening direction is towards the positive Y-axis, the larger the value in the horizontal projection curve, the more edge contours are contained in this row of pixels; the smaller the value, the more non-contours are contained in this row of pixels. Figure 2 As shown, the edge contour is a region with height, including the inner contour line connected to the wafer interior and the outer contour line not connected to the wafer interior. The horizontal projection curve increases in value as it gets closer to the center of the edge contour, reaching its maximum value at the center and then decreasing. In order to calculate relevant positional information through the outer contour line and then perform wafer alignment, this application can locate the center of the edge contour by using the maximum point in the horizontal projection region. Then, by using the minimum point after this maximum point and combining it with a preset vertical coordinate interval, the region is segmented from the image. This region includes part of the edge contour of the positioning slot (including the outer contour line) and the part of the region connected to the outer contour line.

[0122] Alternatively, local minima can be omitted, and appropriate preset coordinate intervals can be set directly based on engineering practice. Image segmentation can then be performed directly using local maxima and preset coordinate intervals.

[0123] In some embodiments of this application, the horizontal projection curve can also be adaptively adjusted to a vertical projection area, the first maximum point can also be adaptively adjusted to the Nth maximum point (N is a positive integer), and the second minimum point can also be adaptively adjusted to the Mth minimum point (M is a positive integer). All of these need to be flexibly handled in combination with the actual scenario, and will not be elaborated here.

[0124] Here, image segmentation is used to obtain the positioning region, including the positioning slot, from an image containing the entire wafer to be positioned. This significantly reduces the amount of data for subsequent processing and improves the efficiency and accuracy of identifying key information about the positioning slot.

[0125] Step 130: Rotate the bounding box of the positioning area multiple times, and extract sub-regions from the rotated positioning area to obtain multiple candidate sub-regions containing slot reference lines, as well as the angle information and region position information of each candidate sub-region. The slot reference line includes the line connecting the two endpoints of the positioning slot and the outer contour of the wafer to be aligned.

[0126] The positioning area only initially defines the positioning slot. However, due to factors such as the image acquisition location and positional deviations of the wafer to be aligned, the reference line for the positioning slot opening in the positioning area (the line connecting the two endpoints where the outer contour of the positioning slot meets the outer contour of the wafer, see [reference]) is not fully defined. Figure 2 There is an unknown angle between the reference line and the bottom edge (horizontal direction) of the positioning area. To accurately locate the slot reference line, this angle needs to be calculated. (Reference) Figure 10 When the wafer positioning groove is positioned on the bearing surface with the groove opening facing directly upwards, this angle (angle 1) is also the wafer deflection angle (angle 2).

[0127] It should also be noted that the connection between the wafer and the positioning slot is an arc with smooth and symmetrical ends. The two endpoints of the slot reference line can be symmetrical points selected from the two arcs, or in some scenarios, the two endpoints can be points on the inner contour line, points on the edge contour, etc.

[0128] Specifically, the bounding box of the positioning area can be rotated multiple times, with each rotation angle being different, resulting in multiple new positioning areas after rotation. At this time, the angle between the groove reference line of the positioning groove and the bottom edge of the positioning area will change. Subsequently, by evaluating the symmetry of the positioning groove in the horizontal direction, the most symmetrical positioning groove can be determined from multiple positioning areas. The angle of the positioning area to which the most symmetrical positioning groove belongs is the deflection angle of the positioning groove of the wafer to be aligned relative to the horizontal direction.

[0129] Alternatively, the bounding box of the positioning area can be kept unchanged, the image of the wafer to be aligned can be rotated, and a new positioning area can be segmented from the rotated image. The angle between the groove reference line of the positioning groove and the bottom edge of the positioning area will also change. After the same post-processing, the required data can be calculated.

[0130] In both of the above rotation methods, the number of rotations, the degree of each rotation, and the total degree of multiple rotations can all be flexibly set according to the actual situation.

[0131] For example, the rotation angle range θ ∈ [-4°, 4°] can be predefined, and the angle search step size Δθ = 0.2°. By rotating the bounding box of the positioning region or rotating the image, 40 positioning regions can be obtained within the angle range with the angle search step size, which can be labeled as Region_θ. Here, θ represents its rotation angle relative to the initial bounding box / image.

[0132] Since the positioning area still includes redundant areas beyond the outer contour line of the positioning slot, in order to reduce the amount of subsequent data processing, improve efficiency, and accurately locate the slot reference line, each positioning area can be further divided into multiple sub-regions, and a candidate sub-region can be selected from them. This candidate sub-region includes the slot reference line, and the slot reference line can be further located through the position information of this candidate sub-region.

[0133] Specifically, when the positioning area is rectangular, the direction indicated by the bottom edge of the positioning area can be used as the first direction. Then, a second direction perpendicular to the first direction can be determined. The positioning area is then divided into multiple sub-regions along the second direction. The heights of the multiple sub-regions can be the same or different, and they can overlap or not overlap. Candidate sub-regions, including the slot reference line, are then selected from these multiple sub-regions. For example... Figure 3 and Figure 4 Within the positioning area, the positioning area is divided into multiple sub-regions with a fixed step size of 10 pixels, and then candidate sub-regions are selected from these sub-regions. Figure 3 The blue sub-region and Figure 4 (the red sub-region).

[0134] Each sub-region corresponds to a location information (the position of the sub-region within the positioning region). Combined with the position of its corresponding positioning region in the image, the regional position information of the region in the entire image can be determined.

[0135] It should be noted that if the rotation method is a rotating bounding box, in the coordinate system of the image to be aligned, the direction indicated by the bottom edge of each positioning area is related to its rotation angle (the first direction is also called the direction of the angle information of the positioning area) and is not parallel to the bottom edge of the image to be aligned; if the rotation method is a rotating image, the direction indicated by the bottom edge of each positioning area is parallel to the bottom edge of the image to be aligned.

[0136] For example, see Figure 3 and Figure 4 , Figure 3 The direction indicated by the bottom edge of the positioning area is the same as the direction indicated by the bottom edge of the image to be aligned. At this time, the rotation angle of the image when the positioning area is obtained needs to be recorded and recorded as the rotation angle of the positioning area. Figure 4 There is an angle between the direction indicated by the bottom edge of the positioning area and the direction indicated by the bottom edge of the image to be aligned. This angle is the rotation angle of the positioning area. Figure 3 and Figure 4 Both methods divide the positioning area into multiple sub-regions.

[0137] The method for selecting candidate sub-regions is similar to the principle of segmenting and locating images from images, as described earlier. Edge contours are dark, while non-contour areas are light. Here, the average grayscale value of each sub-region can be calculated to obtain the grayscale mean curve for each sub-region of the location area. The outer / inner contour line of the positioning groove has one dark side and one light side, resulting in the greatest grayscale variation. Therefore, the gradient curve of the grayscale mean curve (i.e., the average grayscale gradient curve) can be calculated, and the point where the absolute value of the extreme value (gradient amplitude) is greater than a preset fifth threshold can be identified. The sub-region corresponding to this extreme point is then determined as a candidate sub-region. For example, the minimum point in the average grayscale gradient curve where the absolute value of the minimum value is greater than the fifth preset threshold can be identified, and the sub-region corresponding to this minimum point is determined as a candidate sub-region. This allows for the identification of candidate sub-regions, including the area where the outer contour line of the positioning groove, which can determine the groove reference line, is located. This application obtains the overall trend by statistically analyzing the distribution characteristics of small regions and also performs a certain degree of smoothing on the curve to reduce interference errors caused by defects in the location area and improve recognition accuracy.

[0138] For example, calculation Figure 4 The average grayscale value of each sub-region is used to obtain the grayscale mean curve. Further calculations and smoothing are then performed to obtain the average grayscale gradient curve (e.g., ...). Figure 5 As shown), then select the maximum value greater than the threshold P from them, and determine the region where the minimum value point is located as the candidate sub-region (as shown). Figure 4 (The green sub-region in the text).

[0139] Step 140: Calculate the symmetry score of the candidate sub-regions, and select the target sub-region from multiple candidate sub-regions based on the symmetry score.

[0140] The geometry of the positioning slots on the wafer, as well as the slot reference line, are symmetrical with respect to the axis connecting the midpoint of the positioning slot and the center of the wafer. The slot reference line is perpendicular to the line connecting the midpoint of the positioning slot and the center of the wafer. However, as mentioned earlier, the positioning slots in the candidate sub-regions (images) are offset, and there is an angle between the slot reference line and the direction indicated by the bottom edge of the region. Therefore, after obtaining multiple candidate sub-regions, the symmetry score of each candidate sub-region can be calculated using a second direction perpendicular to the direction indicated by the bottom edge of the sub-region as the axis of symmetry. The smaller the angle between the slot reference line and the direction indicated by the bottom edge of the sub-region, the higher the symmetry score. Thus, the target sub-region is selected from multiple candidate sub-regions based on the symmetry score.

[0141] There are several ways to calculate the symmetry score of a sub-region. For example, the symmetry score of a sub-region can be evaluated by fixing the vertical centerline of the sub-region as the axis of symmetry and calculating the difference in gray values ​​between the symmetrical positions of the left and right parts.

[0142] For example, firstly, candidate sub-regions are divided to obtain multiple sub-regions. The size of the sub-regions can be the same or different. Based on the average gray value of the multiple sub-regions, a gray value curve is generated. Then, taking the midpoint of the gray value curve as the starting point, the minimum value points corresponding to the minimum values ​​on the left and right sides that are less than the first preset threshold are found respectively to obtain the left endpoint and the right endpoint.

[0143] The average grayscale value of a subdivided region reflects the proportion of edge contours within that region; a higher average grayscale value indicates a larger proportion of edge contours within that subdivided region. See also... Figure 2 If the positioning groove is U-shaped or V-shaped, the two endpoints where the positioning groove connects to the outer contour of the wafer are points on the arc. Since the wafer is a circle, ideally, after the two endpoints of the groove reference line extend and pass through the contour area, the left side of the left endpoint and the right side of the right endpoint are non-contour areas. The right side of the left endpoint and the left side of the right endpoint are also non-contour areas. The gray value of the non-contour area is significantly greater than that of the vertex (contour area). Therefore, the left and right endpoints can be determined by finding the minimum points on both sides that are less than the first preset threshold. Since most sub-regions do not contain / do not simultaneously contain the left and right endpoints of the positioning groove, if no two minimum points that meet the requirements are found, the sub-region is directly filtered out and no further calculations are performed.

[0144] For example, dividing a sub-region into smaller sub-regions with a width of 100 pixels each (e.g., ...). Figure 6 (This shows the division of some sub-regions), and the average gray value of each sub-region is calculated to generate a gray value curve (e.g., ...). Figure 7 Starting from the midpoint of the grayscale curve, find the minimum points corresponding to the minimum values ​​on both the left and right sides that are less than the first preset threshold (e.g., Figure 7 The two points are labeled, and the sub-regions corresponding to these two points are the left endpoint region and the right endpoint region.

[0145] If the positioning groove is a flat groove, the left end point is a non-contour area to the left and a contour area to the right; the right end point is a non-contour area to the right and a contour area to the left. In this case, the midpoint of the gray value curve is taken as the starting point, the left end point is the inflection point of the curve from rising to stabilizing, and the right end point is the inflection point of the curve from stabilizing to falling.

[0146] Then, based on the first symmetry score, second symmetry score, and edge gradient score of the candidate sub-region calculated based on the left and right endpoints, the first symmetry score, second symmetry score, and edge gradient score are fused according to the preset fusion weight to obtain the symmetry score of the candidate sub-region.

[0147] The first symmetry score can include evaluating the horizontal symmetry of the candidate sub-region using the direction indicated by its bottom edge. The second symmetry score can include evaluating the vertical symmetry of the candidate sub-region using the direction perpendicular to the direction indicated by its bottom edge. Of course, in practical applications, the meanings of the first and second symmetry scores can be interchanged, and their respective indications can be adjusted accordingly; these will not be elaborated further here.

[0148] The notch reference line consists of the line connecting the two endpoints where the outer contour line meets the outer contour line of the wafer. Since the grayscale variation is significant in the regions on either side of the outer contour line, edge gradient scoring can be used to evaluate whether a candidate sub-region contains the optimal notch reference line. Edge gradient scoring characterizes the degree of change in the edge gradient of features within a candidate sub-region; the greater the degree of change, the greater the likelihood that the sub-region contains the outer contour line.

[0149] Finally, based on the pre-set fusion weights, the first symmetry score, the second symmetry score, and the edge gradient score are fused to obtain a symmetry score that comprehensively reflects the degree of symmetry of the candidate sub-region. The higher the symmetry score, the smaller the angle between the slot reference line and the direction indicated by the bottom edge of the sub-region within the candidate sub-region, and the more accurate the angle information of the slot reference line (positioning slot) can be determined.

[0150] The fusion weights here can be flexibly set according to actual needs. For example, the weights of the first symmetry score, the second symmetry score, and the edge gradient score can all be set to 1. They can also be adjusted according to the differences in the importance of the scores in different application scenarios. For example, if the localization slot is a flat slot, the edge gradient score is more important in evaluating symmetry. The weight of the edge gradient score can be set to be greater than the weights of the other two scores. Alternatively, symmetry can be evaluated only by the edge gradient score.

[0151] Specifically, (1) in the candidate sub-regions, the sub-region corresponding to the left endpoint can be determined as the left endpoint region, and the sub-region corresponding to the right endpoint can be determined as the right endpoint region. For example Figure 7 The sub-regions corresponding to the two marked points are the left endpoint region and the right endpoint region.

[0152] (2) The left and right endpoint regions are processed in the first direction indicated by the bottom edge of the candidate sub-region based on the first preset strategy to calculate the first symmetry score of the candidate sub-region. There are multiple ways to implement this. For example, the midpoint region can be determined based on the left and right endpoint regions, and the midline of the midpoint region in the vertical direction can be drawn as the axis of symmetry. The first symmetry score is obtained by analyzing the mirror difference on both sides of the axis of symmetry. The mirror difference includes normalized absolute difference, mean square error, peak signal-to-noise ratio, etc.

[0153] In some embodiments of this application, for example, the left endpoint region can be moved within a preset range along a first direction indicated by the angle information of the candidate sub-region with a first preset step size, starting from the left endpoint region, and the average gray value of each left endpoint region can be calculated to obtain a first left-side gray value change function; the right endpoint region can be moved within a preset range along the opposite direction of the first direction with a first preset step size, starting from the right endpoint region, and the average gray value of each right endpoint region can be calculated to obtain a first right-side gray value change function; the difference between the first left-side gray value change function and the first right-side gray value change function can be calculated to obtain a first symmetry score.

[0154] Starting from the left and right endpoint regions, we extend to the right and left respectively, taking one region to the right of the left endpoint and one region to the left of the right endpoint as the objects of symmetry evaluation. At the same time, we calculate the average value by region to obtain a curve that better reflects the overall trend. This can reduce the interference error caused by defects in the candidate sub-regions and improve the recognition accuracy.

[0155] For example, starting from the left endpoint region, within a 500-pixel range to the right of the left endpoint region, move the left endpoint region (100-pixel wide) in 50-pixel increments, and calculate the average gray value of each region to obtain the first left gray value change function containing 9 discrete values. Similarly, starting from the right endpoint region, obtain the first right gray value change function containing 9 discrete values. Calculate the average of the absolute values ​​of the differences between the first left gray value change function and the first right gray value change function at each position to obtain the first symmetry score.

[0156] (3) The left and right endpoint regions are processed in the second direction based on the second preset strategy to calculate the second symmetry score and edge gradient score of the candidate sub-region. The first and second directions are perpendicular to each other. There are multiple ways to implement this. For example, in the direction parallel to the side of the candidate sub-region, a left comparison region is divided from the candidate sub-region with the left endpoint region as the center, and a right comparison region is divided from the candidate sub-region with the right endpoint region as the center. Then, the difference between the left comparison region and the right comparison region is analyzed to obtain the second symmetry score. The differences include mean squared error, peak signal-to-noise ratio, histogram similarity, etc.

[0157] In some embodiments of this application, the process of calculating the second symmetry score may further include: starting from the left endpoint region, moving the left endpoint region along the second direction within a preset range according to a second preset step size, and calculating the average gray value of each left endpoint region to obtain a second left-side gray value change function; starting from the right endpoint region, moving the right endpoint region along the second direction within a preset range according to a second preset step size, and calculating the average gray value of each right endpoint region to obtain a second right-side gray value change function; and subtracting the second left-side gray value change function from the second right-side gray value change function to obtain the second symmetry score.

[0158] Here, starting from the left and right endpoint regions, we extend vertically, taking the regions containing the left endpoint and the regions containing the right endpoint as the objects of symmetry evaluation. At the same time, we calculate the average value for each region to obtain a curve that better reflects the overall trend. This can reduce the interference error caused by defects in the candidate sub-regions and improve the recognition accuracy.

[0159] For example, taking the left endpoint region as the center position, within a vertical range of 50 pixels above and below the left endpoint region, move the left endpoint region (width 10 pixels) upwards and downwards in a step size of 5 pixels. Calculate the average gray value of each region to obtain the second left gray value change function containing 9 discrete values. Similarly, starting from the right endpoint region, obtain the second right gray value change function containing 9 discrete values. Calculate the average of the absolute values ​​of the differences between the second left gray value change function and the second right gray value change function at each position to obtain the second symmetry score.

[0160] In some embodiments of this application, the process of calculating the edge gradient score may further include: calculating the first derivatives of the second left-side grayscale value change function and the second right-side grayscale value change function respectively to obtain the left-side gradient change function and the right-side gradient change function; calculating the average values ​​of the left-side gradient change function and the right-side gradient change function respectively, and fusing the two average values ​​to obtain the edge gradient score of the candidate sub-region. Fusing the two average values ​​can be done by addition, averaging, etc.

[0161] Then, the symmetry scores can be sorted, and the candidate sub-region with the highest score can be identified as the target sub-region. For example, the symmetry scores can be sorted from smallest to largest, and the sub-region corresponding to the highest-ranked symmetry score can be identified as the target sub-region.

[0162] In some embodiments of this application, after obtaining the sorting results, candidate sub-regions with symmetry scores greater than the set rank can be identified as intermediate sub-regions. These intermediate sub-regions can then be processed more precisely through the aforementioned process to obtain more accurate results. For example, the intermediate sub-regions can be rotated and split using smaller rotation steps and smaller height steps.

[0163] Specifically, within a second preset angle range, the intermediate sub-region is rotated multiple times with a second preset angle step size to obtain multiple rotated intermediate sub-regions and their respective angle information. The second preset angle range is smaller than the first preset angle range, and the second preset angle step size is smaller than the first preset angle step size. The rotated intermediate sub-region is then segmented in the second direction with a second preset height step size to obtain multiple sub-regions and their respective region position information. The second preset height step size is smaller than the first preset height step size. Candidate sub-regions containing the slot reference line are selected from the multiple sub-regions to obtain candidate sub-regions for each of the multiple rotated intermediate sub-regions, as well as the angle and region position information of the candidate sub-regions. The symmetry score of the candidate sub-regions is calculated, and the target sub-region is selected from the multiple candidate sub-regions based on the symmetry score. The processing procedure here can be referred to the previous description and will not be repeated here.

[0164] For example, the intermediate sub-region is rotated in the angle range θ ∈ [-1°, 1°] with an angle search step of 0.01° to obtain 200 intermediate sub-regions. Each intermediate sub-region is then divided into multiple sub-regions with a step of 1 pixel, and candidate sub-regions are selected from them. Finally, the target sub-region is selected from the multiple candidate sub-regions by symmetry scoring.

[0165] Step 150: Determine the point position information of the midpoint of the slot reference line based on the grayscale distribution information of the target sub-region.

[0166] There are several ways to implement this. For example, you can take the previously determined left and right endpoint regions as the starting and ending positions, and calculate the midpoint between these two positions, which is the midpoint of the slot reference line.

[0167] In some embodiments of this application, in order to reduce the interference error caused by defects in the target sub-region, multiple candidate point coordinates can be selected in the initially determined coordinate range containing the midpoint. Then, by taking advantage of the symmetrical geometric features of the regions on both sides of the midpoint, the candidate point coordinates are scored to select more accurate target point coordinates.

[0168] First, the gradient curve of the vertical projection of the target sub-region can be calculated; the coordinate interval of the midpoint of the slot reference line in the target sub-region can be determined, and multiple candidate point coordinates can be selected in the coordinate interval of the gradient curve.

[0169] Based on the geometric characteristics of the positioning groove, it can be seen that the distribution of the groove reference line in the contour area and non-contour area of ​​the image is regular and this distribution is symmetrical. This symmetry can also be reflected in the gradient curve of the area where the groove reference line is located (i.e., the target sub-region). Therefore, this application calculates the gradient curve of the vertical projection of the target sub-region, finds several points that reflect the symmetry through the gradient curve, determines the coordinate interval of the midpoint of the groove reference line based on these points, and selects multiple candidate point coordinates from them.

[0170] (1) Calculate the grayscale curve of the vertical projection of the target sub-region. This curve can reflect the characteristics of the feature change from left to right within the target sub-region. Smooth the grayscale curve to reduce the interference caused by defects. The grayscale change is large when the endpoint of the slot reference line passes through the contour area and the non-contour area. The gradient curve can reflect the degree of grayscale change. Therefore, the first derivative of the smoothed grayscale curve can be obtained to get the gradient curve (e.g., Figure 8 ).

[0171] (2) Determine the coordinate interval of the midpoint of the slot reference line in the target sub-region, and select multiple candidate point coordinates in the coordinate interval of the gradient curve.

[0172] There are multiple ways to implement this. The symmetry of the positioning groove is also reflected in the gradient curve. A central symmetric point of the gradient curve can be selected, and a coordinate interval can be determined using this central symmetric point as the center. Then, multiple candidate point coordinates can be randomly selected from this interval. The process of determining the central symmetric point is as follows: if the overlap rate between the left-hand side of a point on the gradient curve and the original right-hand side after rotating 180 degrees is greater than a preset threshold, then this point is determined as the central symmetric point.

[0173] In some embodiments of this application, the endpoints on the left and right sides can be found first, and then the coordinate range of the midpoint can be calculated based on the endpoints.

[0174] Specifically, starting from the midpoint of the gradient curve, the extreme points corresponding to the extreme values ​​at both ends that match the second preset threshold can be found to obtain the initial left and right endpoints, which are initially identified as the positions of the two endpoints of the slot reference line. Figure 8 For example, starting from the midpoint coordinates, find the minimum point (point 1) along the negative direction where the absolute value of the minimum value is greater than the second preset threshold, and find the maximum point (point 2) along the positive direction where the maximum value is greater than the second preset threshold. These minimum and maximum points are the initial left and initial right endpoints.

[0175] To further reduce the errors caused by wafer edge defects (such as extreme values ​​caused by dust particles, stains, etc. at the endpoints), new extreme points can be found to the right and left respectively based on the initial left and right endpoints. These extreme points correspond to non-wafer areas and will not be disturbed by wafer edge defects, thus obtaining more stable target left and target right endpoints that are symmetrical with respect to the center point of the positioning slot.

[0176] Starting from the initial left endpoint, we can search along the gradient curve in the positive direction for the first maximum value greater than a third preset threshold, and determine this maximum value as the target left endpoint. Similarly, starting from the initial right endpoint, we can search along the gradient curve in the negative direction for the first minimum value greater than a fourth preset threshold, and determine this minimum value as the target right endpoint. Figure 8 For example, starting from point 1, search to the right for the maximum value corresponding to the maximum value greater than the third preset threshold (point 3), and starting from point 2, search to the left for the minimum value corresponding to the minimum value greater than the fourth preset threshold (point 4).

[0177] Then, using the left and right endpoints of the target as the start and end points respectively, a coordinate interval length is obtained. The midpoint of this coordinate interval length (the initial coordinates of the midpoint of the slot reference line) is calculated. Next, smaller coordinate intervals are defined, centered on this midpoint, to determine the preset interval length. Multiple candidate point coordinates are selected from these intervals. Figure 8 For example, determine the midpoint A (not shown in the figure) of the coordinate interval 1 with a length of 400 pixels restricted by points 2 and 4. Then, determine the coordinate interval 2 (not shown in the figure) with a length of 100 pixels centered on the midpoint A. Randomly select M candidate point coordinates (M is a positive integer) in coordinate interval 2.

[0178] (3) Calculate the score of each candidate point coordinate.

[0179] The score of the candidate point coordinates can be used to evaluate its symmetry. The higher the symmetry, the more it conforms to the geometric characteristics of the positioning groove, and the higher the probability that the point is the true midpoint.

[0180] In some embodiments of this application, gradient curves can be used to compare the similarity of curve segments on both sides of the candidate point coordinates. Higher symmetry results in higher similarity and a higher score. Specifically, in the gradient curve coordinate system, starting from the candidate point coordinates, a first curve segment and a second curve segment with the same interval length are selected along the positive and negative x-axis directions, respectively. The similarity between the first and second curve segments is then evaluated to obtain the score for the candidate point coordinates. The interval length can be preset based on actual conditions. Similarity can be calculated using methods such as mean absolute error, mean squared error, correlation coefficient, and Euclidean distance, and can be flexibly selected based on actual conditions, which will not be elaborated further here.

[0181] (4) Based on the sorting results of multiple scores, filter the target point coordinates from multiple candidate point coordinates, and determine the point position information of the midpoint of the slot reference line as the target point coordinates.

[0182] For example, by sorting candidate points by similarity from highest to lowest / lowest to highest, the coordinates of the highest-ranking candidate point are determined as the target point coordinates. The target point coordinates are then the location of the midpoint of the measured slot reference line. The slot reference line and its midpoint can be referenced... Figure 9 .

[0183] 160. The trigger control unit adjusts the position of the wafer to be aligned on the wafer carrier surface based on the angle information, region position information and point position information of the target sub-region, so as to achieve wafer alignment.

[0184] Specifically, the angular deflection of the wafer to be aligned relative to the wafer reference orientation on the wafer carrier surface can be determined based on angular information. For example... Figure 10 The wafer positioning slot is positioned at the preset orientation (wafer reference orientation) on the bearing surface with the slot opening facing directly upwards. The angle information (angle 1) of the target sub-region is the wafer deflection angle information (angle 2). Then, through data such as camera parameters, the mapping relationship between the image coordinate system and the physical coordinate system, the wafer angle deflection can be calculated based on the angle information of the target sub-region.

[0185] Then, based on the regional location information and the point location information, the current position of the midpoint of the slot reference line on the wafer to be aligned is determined; based on the current position and the reference position of the midpoint of the wafer slot reference line on the wafer carrier surface, the lateral offset and longitudinal offset of the wafer to be aligned are calculated.

[0186] Regional location information can pinpoint the location of the target sub-region within the positioning region, while point location information can pinpoint the location of the midpoint within the target sub-region. Based on the location of the positioning region within the image, the position of the midpoint within the image / positioning region is determined. Then, using data such as camera parameters, the mapping relationship between the image coordinate system and the physical coordinate system, the position of the midpoint can be determined based on the measured midpoint and a preset midpoint (the reference position of the midpoint) (e.g., ...). Figure 10 The position data is used to determine the lateral and longitudinal offsets of the wafer to be aligned.

[0187] Finally, the trigger control adjusts the position of the wafer to be aligned on the wafer carrier surface based on the angle deflection, lateral offset, and longitudinal offset to achieve wafer alignment. For example... Figure 10 The wafer to be aligned on the left can be moved and placed in the ideal position on the target bearing surface (such as on the right), thus achieving wafer pre-alignment.

[0188] Based on the symmetrical geometry of the positioning slot, this application, through steps such as rotating the positioning area and evaluating the symmetry of the sub-region, can determine the angle information of the target sub-region as the angle offset information of the positioning slot without identifying the positioning slot and wafer edge contour. This avoids the low contour recognition accuracy caused by high-incidence edge defects and improves the recognition accuracy of angle offset information. Further identification of the target sub-region yields the point position information of the midpoint of the positioning slot opening reference line. Wafer pre-alignment can be directly achieved through the difference between the midpoint position and the ideal midpoint position, as well as the angle deflection information, reducing the consumption of computing and time resources and improving pre-alignment efficiency.

[0189] This application also provides a computer device, such as... Figure 11 As shown, it illustrates a structural schematic diagram of a computer device involved in an embodiment of this application. This computer device can be a terminal or a server, etc. Specifically:

[0190] The computer device may include components such as a processor 401 with one or more processing cores, a memory 402 with one or more computer-readable storage media, a power supply 403, and an input unit 404. Those skilled in the art will understand that... Figure 7 The computer device structure shown does not constitute a limitation on the computer device and may include more or fewer components than shown, or combine certain components, or have different component arrangements. Wherein:

[0191] The processor 401 is the control center of the computer device, connecting various parts of the computer device through various interfaces and lines. It performs various functions and processes data by running or executing computer programs and / or modules stored in the memory 402, and by calling data stored in the memory 402. Optionally, the processor 401 may include one or more processing cores; preferably, the processor 401 may integrate an application processor and a modem processor, wherein the application processor mainly handles the operating system, user interface, and computer programs, and the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into the processor 401.

[0192] The memory 402 can be used to store computer programs and modules. The processor 401 executes various functional applications and data processing by running the computer programs and modules stored in the memory 402. The memory 402 may mainly include a program storage area and a data storage area. The program storage area may store the operating system, computer programs required for at least one function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 402 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device. Accordingly, the memory 402 may also include a memory controller to provide the processor 401 with access to the memory 402.

[0193] The computer device also includes a power supply 403 that supplies power to the various components. Preferably, the power supply 403 can be logically connected to the processor 401 through a power management system, thereby enabling functions such as charging, discharging, and power consumption management through the power management system. The power supply 403 may also include one or more DC or AC power supplies, recharging systems, power fault detection circuits, power converters or inverters, power status indicators, and other arbitrary components.

[0194] The computer device may also include an input unit 404, which can be used to receive input digital or character information and generate keyboard, mouse, joystick, optical or trackball signal inputs related to user settings and function control.

[0195] Although not shown, the computer device may also include a display unit, etc., which will not be described in detail here. Specifically, in this embodiment, the processor 401 in the computer device loads the executable files corresponding to the processes of one or more computer programs into the memory 402 according to the following instructions, and the processor 401 runs the application programs stored in the memory 402 to realize various functions, as follows:

[0196] The process involves: acquiring an image of the wafer to be aligned; segmenting a positioning region from the image, the positioning region containing positioning slots with symmetrical geometry on the wafer to be aligned; rotating the bounding box of the positioning region multiple times and extracting sub-regions from the rotated positioning region to obtain multiple candidate sub-regions containing slot reference lines, as well as angle and region position information for each candidate sub-region. The slot reference lines include the lines connecting the two endpoints where the positioning slots meet the outer contour of the wafer to be aligned; calculating the symmetry score of the candidate sub-regions and selecting a target sub-region from the multiple candidate sub-regions based on the symmetry score; determining the point position information of the midpoint of the slot reference line in the target sub-region based on the grayscale distribution information of the target sub-region; and triggering the control unit to adjust the position of the wafer to be aligned on the wafer carrier surface based on the angle, region, and point position information of the target sub-region to achieve wafer alignment.

[0197] For details on the implementation of each of the above operations, please refer to the previous examples, which will not be repeated here.

[0198] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be performed by a computer program, or by a computer program controlling related hardware. The computer program can be stored in a computer-readable storage medium and loaded and executed by a processor.

[0199] Therefore, embodiments of this application provide a computer-readable storage medium storing a computer program that can be loaded by a processor to execute the steps of any of the wafer pre-alignment methods provided in embodiments of this application. For example, the computer program can execute the following steps:

[0200] The process involves: acquiring an image of the wafer to be aligned; segmenting a positioning region from the image, the positioning region containing positioning slots with symmetrical geometry on the wafer to be aligned; rotating the bounding box of the positioning region multiple times and extracting sub-regions from the rotated positioning region to obtain multiple candidate sub-regions containing slot reference lines, as well as angle and region position information for each candidate sub-region. The slot reference lines include the lines connecting the two endpoints where the positioning slots meet the outer contour of the wafer to be aligned; calculating the symmetry score of the candidate sub-regions and selecting a target sub-region based on the symmetry score; determining the point position information of the midpoint of the slot reference line within the target sub-region based on its grayscale distribution information; and triggering the control unit to adjust the position of the wafer to be aligned on the wafer carrier surface based on the angle, region, and point position information of the target sub-region to achieve wafer alignment. The computer-readable storage medium may include: read-only memory (ROM), random access memory (RAM), a disk, or an optical disk, etc.

[0201] Since the computer program stored in the computer-readable storage medium can execute the steps in any of the wafer pre-alignment methods provided in the embodiments of this application, the beneficial effects that any of the wafer pre-alignment methods provided in the embodiments of this application can achieve can be realized, as detailed in the preceding embodiments, and will not be repeated here.

[0202] This application also provides a computer program product comprising a computer program stored in a computer-readable storage medium. A processor of a computer device reads the computer program from the computer-readable storage medium and executes the computer program, causing the computer device to perform the methods provided in various optional implementations of the above-described wafer pre-alignment method.

[0203] The above provides a detailed description of a wafer pre-alignment method provided by the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A wafer pre-alignment method, characterized by, include: Acquire an image of the wafer to be aligned; The positioning region is segmented from the image, the positioning region comprising positioning grooves with symmetrical geometry in the wafer to be aligned; The bounding box of the positioning area is rotated multiple times, and sub-regions are extracted from the rotated positioning area to obtain multiple candidate sub-regions containing slot reference lines, as well as the angle information and region position information of each candidate sub-region. The slot reference line includes the line connecting the two endpoints of the positioning slot and the outer contour of the wafer to be aligned. Calculate the symmetry score of the candidate sub-regions, and based on the symmetry score, filter the target sub-regions from the plurality of candidate sub-regions; Based on the grayscale distribution information of the target sub-region, determine the point position information of the midpoint of the slot reference line; The trigger control unit adjusts the position of the wafer to be aligned on the wafer carrier surface based on the angle information, region position information and point position information of the target sub-region, so as to achieve wafer alignment.

2. The method according to claim 1, characterized in that, The step of determining the point position information of the midpoint of the slot reference line based on the grayscale distribution information of the target sub-region includes: Calculate the gradient curve of the vertical projection of the target sub-region; Determine the coordinate interval of the midpoint of the slot reference line in the target sub-region, and select multiple candidate point coordinates in the coordinate interval of the gradient curve; Calculate the score for each candidate point coordinate, and based on the sorting results of the multiple scores, filter out the target point coordinates from the multiple candidate point coordinates, and determine the target point coordinates as the point position information of the midpoint of the slot reference line.

3. The method according to claim 2, characterized in that, Determining the coordinate interval of the midpoint of the slot reference line in the target sub-region includes: Taking the midpoint coordinates of the gradient curve as the starting point, the left endpoint and right endpoint of the target are determined on both sides of the midpoint coordinates respectively; Based on the left endpoint and the right endpoint of the target, the coordinate range of the curve segment to be extracted is determined, and the coordinates of the midpoint of the coordinate range are determined as the initial coordinates of the midpoint of the slot reference line. Based on the initial point coordinates and the preset interval length, the coordinate interval of the midpoint of the slot reference line in the target sub-region is determined.

4. The method according to claim 3, characterized in that, The calculation of the score for each candidate point coordinate includes: In the coordinate system of the gradient curve, starting from the coordinates of the candidate point, a first curve segment and a second curve segment with the same interval length are selected along the positive and negative x-axis directions, respectively. The similarity between the first curve segment and the second curve segment is evaluated to obtain a score for the coordinates of the candidate point.

5. The method according to claim 3, characterized in that, Taking the midpoint coordinates of the gradient curve as the starting point, the left and right endpoints of the target are determined on both sides of the midpoint coordinates, including: Starting from the midpoint coordinates of the gradient curve, find the extreme points corresponding to the extreme values ​​at both ends that match the second preset threshold, and obtain the initial left endpoint and the initial right endpoint. Starting from the initial left endpoint, search along the positive direction on the gradient curve for the first maximum value corresponding to a maximum value greater than the third preset threshold, and determine the maximum value point as the target left endpoint; Starting from the initial right endpoint, search along the negative direction on the gradient curve for the first minimum value corresponding to a minimum value greater than the fourth preset threshold, and determine the minimum point as the target right endpoint.

6. The method according to claim 1, characterized in that, The trigger control unit adjusts the position of the wafer to be aligned on the wafer carrier surface based on the angle information, region position information, and point position information of the target sub-region, in order to achieve wafer alignment, including: Based on the angle information, determine the angular deflection of the wafer to be aligned relative to the wafer reference orientation on the wafer carrier surface; Based on the region location information and the point location information, the lateral offset and longitudinal offset of the wafer to be aligned relative to the wafer reference position on the wafer bearing surface are determined. The control is triggered to adjust the position of the wafer to be aligned on the wafer carrier surface based on the angle deflection, the lateral offset, and the longitudinal offset, so as to achieve wafer alignment.

7. The method according to claim 6, characterized in that, The step of determining the lateral and longitudinal offsets of the wafer to be aligned relative to the wafer reference position on the wafer carrier surface based on the region location information and the point location information includes: Based on the region location information and the point location information, determine the current position of the midpoint of the slot reference line on the wafer to be aligned; Based on the current position and the reference position of the midpoint of the wafer slot reference line on the wafer carrier surface, the lateral offset and longitudinal offset of the wafer to be aligned are calculated.

8. The method according to claim 1, characterized in that, The calculation of the symmetry score of the candidate sub-region includes: The candidate sub-regions are divided into multiple sub-regions with equal width. Based on the average gray value of the multiple sub-regions, a gray value curve is generated. Starting from the midpoint of the gray value curve, the minimum value points corresponding to the minimum values ​​on the left and right sides that are less than the first preset threshold are found respectively to obtain the left endpoint and the right endpoint. Based on the left and right endpoints, calculate the first symmetry score, the second symmetry score, and the edge gradient score of the candidate sub-region; Based on preset fusion weights, the first symmetry score, the second symmetry score, and the edge gradient score are fused to obtain the symmetry score of the candidate sub-region.

9. The method according to claim 8, characterized in that, The calculation of the first symmetry score, second symmetry score, and edge gradient score of the candidate sub-region based on the left and right endpoints includes: In the candidate sub-regions, the sub-region corresponding to the left endpoint is determined as the left endpoint region, and the sub-region corresponding to the right endpoint is determined as the right endpoint region; The left and right endpoint regions are processed based on a first preset strategy in the first direction indicated by the angle information of the candidate sub-region to calculate the first symmetry score of the candidate sub-region; The left and right endpoint regions are processed in the second direction based on a second preset strategy to calculate the second symmetry score and edge gradient score of the candidate sub-region, wherein the first and second directions are perpendicular to each other.

10. The method according to claim 9, characterized in that, The first direction indicated by the angle information of the candidate sub-region is used to process the left and right endpoint regions based on a first preset strategy to calculate a first symmetry score for the candidate sub-region, including: Starting from the left endpoint region, the left endpoint region is moved within a preset range along the first direction indicated by the angle information of the candidate sub-region according to the first preset step size, and the average gray value of each left endpoint region is calculated to obtain the first left gray value change function. Starting from the right endpoint region, the right endpoint region is moved within a preset range in the opposite direction of the first direction according to a first preset step size, and the average gray value of each right endpoint region is calculated to obtain the first right gray value change function. The first symmetry score is obtained by subtracting the gray value change function on the left and the gray value change function on the right.

11. The method according to claim 9, characterized in that, The step of processing the left and right endpoint regions in the second direction based on a second preset strategy to calculate the second symmetry score and edge gradient score of the candidate sub-region includes: Starting from the left endpoint region, the left endpoint region is moved within a preset range along the second direction with a second preset step size, and the average gray value of each left endpoint region is calculated to obtain the second left gray value change function. Starting from the right endpoint region, the right endpoint region is moved within a preset range along the second direction with a second preset step size, and the average gray value of each right endpoint region is calculated to obtain the second right gray value change function. The second symmetry score is obtained by subtracting the second left-side grayscale value change function and the second right-side grayscale value change function. The edge gradient score of the candidate sub-region is calculated based on the second left gray value change function and the second right gray value change function.

12. The method according to claim 11, characterized in that, The step of calculating the edge gradient score of the candidate sub-region based on the second left-side grayscale value change function and the second right-side grayscale value change function includes: Calculate the first derivatives of the second left-side grayscale value change function and the second right-side grayscale value change function respectively to obtain the left-side gradient change function and the right-side gradient change function; The average values ​​of the left-side gradient change function and the right-side gradient change function are calculated separately, and the two average values ​​are fused to obtain the edge gradient score of the candidate sub-region.

13. The method according to claim 1, characterized in that, The process of rotating the bounding box of the positioning region multiple times and extracting sub-regions from the rotated positioning region to obtain multiple candidate sub-regions containing the slot reference line, as well as the angle information and region position information of each candidate sub-region, includes: Within a first preset angle range, the bounding box of the positioning area is rotated multiple times with a first preset angle step size to obtain multiple rotated positioning areas and their respective angle information. The rotated positioning area is divided along a second direction perpendicular to the first direction indicated by the angle information of the positioning area, with a first preset height step, to obtain multiple sub-regions and their respective regional position information. Candidate sub-regions containing slot reference lines are selected from the plurality of sub-regions to obtain the candidate sub-regions of each of the plurality of rotated positioning regions, as well as the angle information and region position information of the candidate sub-regions.

14. The method according to claim 13, characterized in that, The step of filtering candidate sub-regions containing the slot reference line from the plurality of sub-regions includes: Based on the average gray value of the sub-region, the average gray value curve of the rotated positioning region is determined, and the first derivative of the average gray value curve is obtained to obtain the average gray value gradient curve. The minimum point in the average gray-scale gradient curve whose absolute value is greater than a fifth preset threshold is obtained, and the sub-region corresponding to the minimum point is determined as a candidate sub-region.

15. A wafer pre-alignment apparatus, characterized in that, include: The acquisition module is used to acquire images of the wafer to be aligned; A segmentation module is used to segment a positioning region from the image, the positioning region comprising positioning grooves with symmetrical geometry in the wafer to be aligned; The candidate module is used to rotate the bounding box of the positioning area multiple times and extract sub-regions from the rotated positioning area to obtain multiple candidate sub-regions containing slot reference lines, as well as the angle information and region position information of each candidate sub-region. The slot reference line includes the line connecting the two endpoints of the positioning slot and the outer contour of the wafer to be aligned. A calculation module is used to calculate the symmetry score of the candidate sub-regions and, based on the symmetry score, filter the target sub-regions from the plurality of candidate sub-regions; The determination module is used to determine the point position information of the midpoint of the slot reference line in the target sub-region based on the grayscale distribution information of the target sub-region; The alignment module is used to trigger the control unit to adjust the position of the wafer to be aligned on the wafer carrier surface based on the angle information, region position information and point position information of the target sub-region, so as to achieve wafer alignment.

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