Wafer alignment method prior to bonding and related apparatus

Abstract

Embodiments of the present application disclose a wafer alignment method before bonding and a related device. The method can acquire a first image and at least one second image collected between a first wafer and a second wafer placed oppositely, the first image including an image of a first positioning groove at an edge of the first wafer and an image of a second positioning groove at an edge of the second wafer; determine a first boundary line in the first image, the first boundary line being located between the first positioning groove and the second positioning groove, and identify first angle information of a notch reference line of the first positioning groove and second angle information of a notch reference line of the second positioning groove, the notch reference line including a line between two end points where the positioning groove meets an outer contour of the wafer; determine an offset of the first wafer relative to the second wafer based on the first angle information, the second angle information and the second image; and trigger an adjusting unit to move the second wafer according to the offset, so that the second wafer is aligned with the first wafer, effectively improving the alignment accuracy.

Description

Technical Field

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

[0002] In semiconductor manufacturing, precise wafer alignment is a critical prerequisite for ensuring process implementation and is crucial throughout the entire wafer manufacturing process. For example, two wafers need to be aligned before wafer bonding. Related technologies require accurate identification of the edge contours of the two wafers to determine their offset before bonding. However, due to the inherent characteristics of semiconductor manufacturing processes, the edges of the positioning grooves are often high-defect areas, frequently accompanied by random dust particles and other defects. Furthermore, the positioning grooves directly affect the accuracy of identifying the angular offset between wafers, resulting in low wafer alignment precision. Summary of the Invention

[0003] This application provides a wafer alignment method and related equipment before bonding, which can improve the wafer alignment accuracy before bonding.

[0004] This application discloses a wafer alignment method before bonding, including:

[0005] Acquire a first image and at least one second image between two oppositely placed first and second wafers, the first image including an image of a first positioning groove at the edge of the first wafer and an image of a second positioning groove at the edge of the second wafer, and the second image including an image of a portion of the edge of the first wafer and an image of a portion of the edge of the second wafer;

[0006] In the first image, a first dividing line is determined, which is located between the first positioning groove and the second positioning groove. The first angle information of the groove reference line of the first positioning groove and the second angle information of the groove reference line of the second positioning groove are identified. The groove reference line includes the line connecting the two endpoints of the positioning groove and the outer contour of the wafer.

[0007] Based on the angular offset and position offset, the adjustment unit is triggered to move the second wafer, so that the second wafer is aligned with the first wafer.

[0008] This application discloses a wafer alignment apparatus before bonding, comprising:

[0009] An image module is used to acquire a first image and at least one second image between two oppositely placed first wafers, the first image including an image of a first positioning groove at the edge of the first wafer and an image of a second positioning groove at the edge of the second wafer, and the second image including an image of a portion of the edge of the first wafer and an image of a portion of the edge of the second wafer;

[0010] An angle module is used to determine a first dividing line in a first image, the first dividing line being located between the first positioning groove and the second positioning groove, and to identify first angle information of the groove reference line of the first positioning groove and second angle information of the groove reference line of the second positioning groove, the groove reference line including the line connecting the two endpoints of the positioning groove to the outer contour of the wafer.

[0011] The offset module is used to determine the angular offset and position offset of the first wafer relative to the second wafer based on the first angle information, the second angle information, and the second image.

[0012] The adjustment module is used to trigger the adjustment unit to move the second wafer according to the angular offset and position offset, so that the second wafer is aligned with the first wafer.

[0013] In some embodiments of this application, the angle module is specifically used for:

[0014] A first positioning region and a second positioning region are segmented from the first image. The first positioning region is located on one side of the first dividing line and includes the first positioning groove in the image. The second positioning region is located on the other side of the first dividing line and includes the second positioning groove in the image. The first positioning groove and the second positioning groove have symmetrical geometric shapes. The first positioning region and the second positioning region are axially symmetrical about the first dividing line.

[0015] The bounding box of the positioning area is rotated multiple times, and a target sub-region is selected from multiple sub-regions based on the symmetry score of the sub-regions of the rotated positioning area. The target sub-region includes a slot reference line, which is a line connecting the two endpoints of the positioning slot and the outer contour of the wafer.

[0016] The rotation angle information of the positioning area to which the target sub-region belongs is determined as the angle information of the slot reference line of the positioning groove, and the first angle information of the slot reference line of the first positioning groove and the second angle information of the slot reference line of the second positioning groove are obtained.

[0017] In some embodiments of this application, the angle module is specifically used for:

[0018] 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 the slot reference line, as well as the regional position information of each candidate sub-region.

[0019] Calculate the symmetry score of the candidate sub-regions, and filter the target sub-region from multiple candidate sub-regions based on the symmetry score.

[0020] In some embodiments of this application, the angle module is specifically used for:

[0021] 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.

[0022] 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;

[0023] 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.

[0024] In some embodiments of this application, the angle module is specifically used for:

[0025] 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.

[0026] 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;

[0027] 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.

[0028] In some embodiments of this application, the angle module is specifically used for:

[0029] 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.

[0030] 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.

[0031] 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.

[0032] In some embodiments of this application, the angle module is specifically used for:

[0033] 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;

[0034] 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.

[0035] 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.

[0036] 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.

[0037] In some embodiments of this application, the angle module is specifically used for:

[0038] 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;

[0039] 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.

[0040] In some embodiments of this application, the angle module is specifically used for:

[0041] 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.

[0042] 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.

[0043] 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.

[0044] In some embodiments of this application, the angle module is specifically used for:

[0045] 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.

[0046] 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.

[0047] In some embodiments of this application, the angle module is specifically used for:

[0048] The symmetry scores are sorted, and the target sub-region is selected from multiple candidate sub-regions based on the sorting results.

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

[0050] The candidate sub-regions corresponding to symmetry scores greater than the set ranking are identified as the middle sub-regions;

[0051] 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.

[0052] 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.

[0053] 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;

[0054] 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.

[0055] In some embodiments of this application, the position offset includes a first lateral offset and a second lateral offset, and the offset module is specifically used for:

[0056] Based on the first angle information and the second angle information, calculate the angular offset of the first wafer relative to the second wafer and the first position offset information;

[0057] Based on the second image, at least one second position offset information of the first wafer relative to the second wafer is determined;

[0058] The first position offset information and the second position offset information are fused together to obtain the position offset of the first wafer relative to the second wafer.

[0059] In some embodiments of this application, the offset module is specifically used for:

[0060] Construct a third angle information, which is symmetrical to the second angle information about the first boundary line;

[0061] Based on the angle difference between the third angle information and the first angle information, the angle offset of the first wafer relative to the second wafer is calculated;

[0062] Construct a first reference line, which is perpendicular to the first dividing line and bisects the first image.

[0063] Based on the third angle information and the first angle information, the intersection point of the slot reference line of the first wafer and the first reference line, and the intersection point of the slot reference line of the second wafer and the first reference line are determined.

[0064] The first position offset information of the first wafer relative to the second wafer is determined based on the distance between the two intersection points.

[0065] 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 alignment method before bonding provided in this application.

[0066] 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 alignment method before bonding provided in embodiments of this application.

[0067] 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 alignment method before bonding provided in embodiments of this application.

[0068] This application can acquire a first image and at least one second image between two relatively placed first and second wafers. The first image includes an image of a first positioning groove on the edge of the first wafer and an image of a second positioning groove on the edge of the second wafer. A first boundary line is determined in the first image, and the first angle information of the groove reference line of the first positioning groove located on both sides of the first boundary line and the second angle information of the groove reference line of the second positioning groove are identified. The groove reference line includes the line connecting the two endpoints of the positioning groove and the outer contour of the wafer. Compared with related technologies, this application does not need to identify the complete edge contour where defects are common. Instead, it determines the angle information of the two wafers through the groove reference line, thereby determining the deflection amount and performing wafer alignment before bonding, effectively improving the wafer alignment accuracy. Attached Figure Description

[0069] 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.

[0070] Figure 1This is a schematic diagram of a wafer alignment apparatus for a wafer alignment method prior to bonding provided in an embodiment of this application;

[0071] Figure 2 This is a schematic diagram of the visual components of the wafer alignment method before bonding provided in the embodiments of this application;

[0072] Figure 3 This is a schematic flowchart of the wafer alignment method before bonding provided in the embodiments of this application;

[0073] Figure 4 This is a schematic diagram of the image acquisition position of the wafer alignment method before bonding provided in the embodiments of this application;

[0074] Figure 5 This is a schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0075] Figure 6 This is another schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0076] Figure 7 This is another schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0077] Figure 8 This is a schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0078] Figure 9 This is another schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0079] Figure 10 This is another schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0080] Figure 11 This is a schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0081] Figure 12 This is another schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0082] Figure 13 This is another schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0083] Figure 14 This is another schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0084] Figure 15 This is a schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0085] Figure 16 This is another schematic diagram of the wafer alignment method before bonding provided in the embodiments of this application;

[0086] Figure 17 This is a schematic diagram of the structure of the computer device provided in the embodiments of this application. Detailed Implementation

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] This application discloses a wafer alignment method and related equipment before bonding. The method includes: acquiring a first image and at least one second image between two oppositely placed first and second wafers, the first image including an image of a first positioning groove on the edge of the first wafer and an image of a second positioning groove on the edge of the second wafer; determining a first boundary line in the first image and identifying first angle information of the groove reference line of the first positioning groove located on both sides of the first boundary line and second angle information of the groove reference line of the second positioning groove, the groove reference line including a line connecting the two endpoints of the positioning groove and the outer contour of the wafer; determining an angular offset and a positional offset of the first wafer relative to the second wafer based on the first angle information, the second angle information, and the second image; and triggering an adjustment unit to move the second wafer according to the angular offset and the positional offset, so that the second wafer is aligned with the first wafer.

[0092] In this embodiment, the wafer alignment method before bonding can be applied to a wafer alignment device, which is located in the wafer bonding system.

[0093] like Figure 1 As shown, the wafer alignment device includes a base 200, a first support 300, a second support 400, an adjustment assembly 500, at least two vision components 100, and a control unit 600.

[0094] A first support member 300 is mounted on a base 200 and is used to support a second wafer W2. A second support member 400 is longitudinally spaced from the first support member 300 and is used to support a first wafer W1. An adjustment assembly 500 is mounted on the base 200 and connected to the second support member 400. The adjustment assembly 500 is used to move the second support member 400 relative to the first support member 300.

[0095] See Figure 2 Each vision component 100 includes a camera 110, a light source 120, a semi-transparent beam splitter 130, and a beam splitter 140, arranged sequentially along a preset axis L1. The light source 120 is located on one side of the preset axis L1, with its light-emitting surface facing the semi-transparent beam splitter 130. The emitted light from the light source 120 can be reflected by the semi-transparent beam splitter 130 and projected onto the beam splitter 140. The beam splitter 140 extends between a first wafer W1 and a second wafer W2 placed opposite each other. The beam splitter 140 includes a first inclined surface 141 inclined towards the first wafer and a second inclined surface 142 inclined towards the second wafer, symmetrically arranged. The camera 110 is used to acquire an image to be processed, which includes images of the first wafer and the second wafer.

[0096] At least two vision components 100 are distributed around the second carrier 400. With the first carrier 300 carrying the second wafer W2 and the second carrier 400 carrying the first wafer W1, the beam-splitting prism 140 of each vision component 100 is positioned laterally at the edge of the second wafer W2 and longitudinally between the second wafer W2 and the first wafer W1. Each vision component 100 is used to acquire a corresponding image to be processed. The image to be processed includes images of portions of the edges of the first wafer W1 and portions of the edges of the second wafer W2.

[0097] The control unit 600 is communicatively connected to the vision component 100 and the adjustment component 500. The control unit 600 can calculate the offset information of the first wafer W1 relative to the second wafer W2 using the wafer alignment method before bonding in this application. The control unit 600 is used to control the adjustment component 500 to move the second carrier 400 according to the offset information, so that the second wafer W2 is aligned with the first wafer W1.

[0098] The control unit 600 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 the following: 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.

[0099] 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.

[0100] The above is merely an illustrative example and does not constitute a limitation on the application scenarios of this application. The wafer alignment method before bonding in this application will be further described below with reference to embodiments.

[0101] Please see Figure 3 , Figure 3 A flowchart of the wafer alignment method before bonding is shown in this application. The wafer alignment method before bonding may include:

[0102] Step 110: Acquire a first image and at least one second image between two oppositely placed first and second wafers. The first image includes an image of a first positioning groove at the edge of the first wafer and an image of a second positioning groove at the edge of the second wafer. The second image includes an image of a portion of the edge of the first wafer and an image of a portion of the edge of the second wafer.

[0103] The wafer here can include the wafer itself, or it can include carriers, interposers, etc. that need to be bonded to the wafer / chip in advanced processes. The wafer shape can be circular, rectangular, etc.

[0104] It can be done as follows Figure 2 The visual component shown is placed between the first wafer and the second wafer to acquire a first image and at least one second image.

[0105] For example, it can be like Figure 1 The wafer alignment device is equipped with three vision components, the positions of which can be found in [reference needed]. Figure 4 The vision component 100a can acquire an image at position TP1 that simultaneously includes the positioning slots of the first wafer and the positioning slots of the second wafer (e.g., Figure 5 The first image shown), vision components 100b and 100c can acquire images that simultaneously include the edges of the upper and lower wafer portions at positions TP2 and TP3, respectively (e.g., the first image shown). Figure 6 and Figure 7 (The two second images shown).

[0106] Step 120: Determine a first dividing line in the first image. The first dividing line is located between the first positioning groove and the second positioning groove. Identify the first angle information of the groove reference line of the first positioning groove and the second angle information of the groove reference line of the second positioning groove. The groove reference line includes the line connecting the two endpoints of the positioning groove and the outer contour of the wafer.

[0107] The first dividing line can be determined based on the symmetry axis calibration information of the visual component of the acquired image. Typically, the first dividing line is the center line of the first image in the bottom or side direction, for example... Figure 8 The vertical centerline of the first image is determined, which is the first dividing line T1.

[0108] Then, the first angle information of the slot reference line of the first positioning slot located on both sides of the first boundary line T1 and the second angle information of the slot reference line of the second positioning slot can be identified. Positioning slots can be flat or notched, with notch shapes such as U-shapes or V-shapes. These shapes are all symmetrical geometries. Positioning slots can determine the crystal orientation of the marked silicon wafer and enable the wafer to be correctly positioned and aligned in semiconductor manufacturing equipment. The slot reference line includes the line connecting the two endpoints where the positioning slot meets the outer contour of the wafer. Figure 8As shown, the first angle information of the slot reference line cc and the second angle information of the slot reference line kk can be identified.

[0109] First, a first positioning region containing a first positioning groove on one side of the first dividing line and a second positioning region containing a second positioning groove on the other side of the first dividing line can be segmented from the first image. The positioning groove has a symmetrical geometric shape, and the first and second positioning regions are symmetrical about the first dividing line. Figure 8 The first positioning region N1 and the second positioning region N2 are divided symmetrically about the first dividing line. This division can be achieved by using pre-set coordinates of the first and second regions on the first image.

[0110] In some embodiments of this application, since the wafer has undergone at least one round of alignment before bonding, the angular offset between the two wafers is limited, and the difference between the two positioning slots in the first image is not significant. Alternatively, a positioning area on one side of the first dividing line can be determined first, and then, using the coordinate position of the positioning area, the other positioning area on the other side can be directly divided by taking advantage of the axial symmetry of the two positioning areas about the first dividing line.

[0111] The process of determining the positioning area on one side may include: firstly dividing the preliminary positioning area with the first dividing line as the edge, then calculating the horizontal projection curve of the preliminary positioning, and obtaining the first maximum point and the second minimum point in the horizontal projection curve. Based on the maximum point, the minimum point and the preset coordinate interval, the positioning area containing the positioning groove is divided from the preliminary positioning area.

[0112] 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, 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 8 As shown, the edge contour is a region with height, including the inner contour line connected to the wafer and the outer contour line not connected to the wafer. 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 position information using the outer contour line, this application locates the center of the edge contour by using the maximum point in the horizontal projection region. Then, using the minimum point after this maximum point and combining it with a preset vertical coordinate interval, the positioning region is divided from the initial positioning region. This positioning 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.

[0113] 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.

[0114] Then, the bounding box of the positioning area can be rotated multiple times, and the target sub-region can be selected from multiple sub-regions based on the symmetry score of the sub-regions of the rotated positioning area. The target sub-region includes the slot reference line formed by the connection between the two endpoints of the positioning slot and the outer contour of the wafer.

[0115] This process can be achieved through the following steps:

[0116] 1. 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 the slot reference line, as well as the regional position information of each candidate sub-region.

[0117] The positioning area is only a preliminary division of the positioning groove. The reference line of the groove opening in the positioning area has an unknown angle with the bottom edge (horizontal direction) of the positioning area. To accurately position the groove opening reference line, this angle needs to be solved.

[0118] It should also be noted that the connection between the wafer and the positioning slot is an arc, with the left and right segments being smooth and symmetrical. 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 also be points on the inner contour line, points on the edge contour, etc.

[0119] 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 in the positioning area 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 first wafer relative to the horizontal direction.

[0120] Alternatively, the bounding box of the positioning area can be kept unchanged, the initial positioning area can be rotated, and a new positioning area can be segmented from the rotated initial positioning area. 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 also be calculated.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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 9 and Figure 10 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 9 The blue sub-region and Figure 10 (the red sub-region).

[0125] 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 region's location information in the first image can be determined.

[0126] It should be noted that if the rotation method is a rotated 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 rotated image, the direction indicated by the bottom edge of each positioning area is parallel to the bottom edge of the image to be aligned.

[0127] For example, see Figure 9 and Figure 10 , Figure 9 The direction indicated by the bottom edge of the positioning area is the same as the direction indicated by the bottom edge of the first image. Figure 10 The direction indicated by the bottom edge of the positioning area is at an angle to the direction indicated by the bottom edge of the first image. This angle is the rotation angle of the positioning area. Figure 9 and Figure 10Both methods divide the positioning area into multiple sub-regions.

[0128] 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.

[0129] For example, calculation Figure 10 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 11 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 10 (The green sub-region in the text).

[0130] 2. 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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 12 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 circular, 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.

[0135] For example, dividing a sub-region into smaller sub-regions with a width of 100 pixels each (e.g., ...). Figure 13 (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 14 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 14 The two points are labeled, and the sub-regions corresponding to these two points are the left endpoint region and the right endpoint region.

[0136] 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.

[0137] 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.

[0138] 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 also 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.

[0139] 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.

[0140] 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.

[0141] (1) Within 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 14 The sub-regions corresponding to the two marked points are the left endpoint region and the right endpoint region.

[0142] (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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] (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.

[0147] In some embodiments of this application, the process of calculating the second symmetry score can be as follows: starting from the left endpoint region, the left endpoint region is moved along the second direction within a preset range by 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 along the second direction within a preset range by 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 difference between the second left gray value change function and the second right gray value change function is calculated to obtain the second symmetry score.

[0148] 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 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.

[0149] 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.

[0150] In some embodiments of this application, the process of calculating the edge gradient score includes, for example, calculating the first derivatives of the second left-side grayscale value change function and the second right-side grayscale value change function 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 through addition, averaging, etc.

[0151] 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.

[0152] 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.

[0153] 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 information 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.

[0154] 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.

[0155] Therefore, this application first obtains multiple candidate rotation angles for the slot reference line through multiple rotations. Then, utilizing the symmetrical geometry of the positioning slot, it performs symmetry analysis on each candidate sub-region containing the slot reference line based on statistical data to find the target sub-region with the best symmetry. See [link to relevant documentation]. Figure 8 The symmetry of the slot reference line cc in target sub-region 1 is the best. The deflection angle of the positioning area to which target sub-region 1 belongs is the angle information of the slot reference line cc. Similarly, the deflection angle of the positioning area to which target sub-region 2 belongs is the angle information of the slot reference line kk.

[0156] Step 130: Based on the first angle information, the second angle information, and the second image, determine the angular offset and position offset of the first wafer relative to the second wafer.

[0157] The angular offset and the first position offset of the first wafer relative to the second wafer can be calculated based on the first angle information and the second angle information.

[0158] Specifically, a third angle information can be constructed, which is symmetrical to the second angle information about the first boundary line; based on the angle difference between the third angle information and the first angle information, the angle offset of the first wafer relative to the second wafer is calculated; a first reference line is constructed, which is perpendicular to the first boundary line and bisects the first image; based on the third angle information and the first angle information, the intersection point of the notch reference line of the first wafer and the first reference line, and the intersection point of the notch reference line of the second wafer and the first reference line are determined; based on the distance between the two intersection points, the first position offset information of the first wafer relative to the second wafer is determined.

[0159] For example, see Figure 15 The notch reference line J1 belongs to the positioning notch Q1 of the first wafer, and the notch reference line F1 belongs to the positioning notch Q2 of the second wafer. A mirror positioning notch P1, which is symmetrical to the positioning notch Q1 about the first dividing line T1, is constructed. The notch reference line F2 belongs to the mirror positioning notch Q2. Based on the symmetry, the angle of the notch reference line F2 can be determined based on the angle of the notch reference line J1. A first reference line V1 is constructed. The first reference line V1 is perpendicular to the first dividing line T1 and bisects this figure. The notch reference line F1 and the first reference line V1 intersect at point K1, and the notch reference line F2 and the first reference line V1 intersect at point K2. The distance between points K1 and K2 is the first position offset information of the first wafer relative to the second wafer. Based on the angle difference between the notch reference lines F2 and F1, the angle offset of the first wafer relative to the second wafer can be determined.

[0160] Based on the second image, at least one second position offset information of the first wafer relative to the second wafer is determined; the first position offset information and the second position offset information are fused to obtain the first lateral offset and the second lateral offset of the first wafer relative to the second wafer.

[0161] Determining the second position offset information from the second image can be, for example... Figure 16 Based on the boundary line information of the visual component 100 that acquires the second image, a second boundary line T2 is determined in the second image. Feature recognition is performed in the second image to obtain a third contour line Q3 and a fourth contour line Q4 located on both sides of the second boundary line T2. The third contour line Q3 corresponds to a portion of the edge of the second wafer W2, and the fourth contour line Q4 corresponds to a portion of the edge of the first wafer W1. A second mirror line P2 and a second reference line V2 are constructed. The second mirror line P2 and the fourth contour line Q4 are symmetrical about the second boundary line T2, and the second reference line V2 is parallel to the second boundary line T2 and intersects the third contour line Q3 and the second mirror line P2. The third intersection point F3 of the third contour line Q3 and the second reference line V2 is obtained, and the fourth intersection point F4 of the second mirror line P2 and the second reference line V2 is obtained. The distance between the third intersection point F3 and the fourth intersection point F4 is used as the second position offset information.

[0162] Then, by combining the resolution calibration information, coordinate axis calibration information, and at least two positional offset information of the vision component, the first lateral offset and the second lateral offset of the first wafer relative to the second wafer can be fitted. This can be achieved through methods such as least squares, which will not be elaborated upon here.

[0163] Step 140: Based on the angular offset and position offset, trigger the adjustment unit to move the second wafer so that the second wafer is aligned with the first wafer.

[0164] For example, the adjustment unit moves the second wafer by a first lateral offset in the X-axis direction, a second lateral offset in the Y-axis direction, and a rotation angle offset in the T-axis, thereby achieving alignment of the first and second wafers before bonding.

[0165] This application can acquire a first image and at least one second image between two relatively placed first and second wafers. The first image includes an image of a first positioning groove on the edge of the first wafer and an image of a second positioning groove on the edge of the second wafer. A first boundary line is determined in the first image, and the first angle information of the groove reference line of the first positioning groove located on both sides of the first boundary line and the second angle information of the groove reference line of the second positioning groove are identified. The groove reference line includes the line connecting the two endpoints of the positioning groove and the outer contour of the wafer. Compared with related technologies, this application does not need to identify the complete edge contour where defects are common. Instead, it determines the angle information of the two wafers through the groove reference line, thereby determining the deflection amount and performing wafer alignment before bonding, effectively improving the wafer alignment accuracy.

[0166] This application also provides a computer device, such as... Figure 17 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:

[0167] 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 17 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:

[0168] 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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:

[0173] Acquire a first image and at least one second image between two relatively placed wafers. The first image includes an image of a first positioning groove on the edge of the first wafer and an image of a second positioning groove on the edge of the second wafer. Determine a first boundary line in the first image and identify first angle information of the groove reference line of the first positioning groove located on both sides of the first boundary line and second angle information of the groove reference line of the second positioning groove. The groove reference line includes a line connecting the two endpoints of the positioning groove to the outer contour of the wafer. Based on the first angle information, the second angle information, and the second image, determine the angular offset and positional offset of the first wafer relative to the second wafer. According to the angular offset and positional offset, trigger an adjustment unit to move the second wafer so that the second wafer is aligned with the first wafer.

[0174] For details on the implementation of each of the above operations, please refer to the previous examples, which will not be repeated here.

[0175] 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.

[0176] Therefore, embodiments of this application provide a computer-readable storage medium storing a computer program that can be loaded by a processor to execute steps in any of the pre-bonding wafer alignment methods provided in embodiments of this application. For example, the computer program can execute the following steps:

[0177] Acquire a first image and at least one second image between two relatively placed wafers. The first image includes an image of a first positioning groove on the edge of the first wafer and an image of a second positioning groove on the edge of the second wafer. Determine a first boundary line in the first image and identify first angle information of the groove reference line of the first positioning groove located on both sides of the first boundary line and second angle information of the groove reference line of the second positioning groove. The groove reference line includes a line connecting the two endpoints of the positioning groove to the outer contour of the wafer. Based on the first angle information, the second angle information, and the second image, determine the angular offset and positional offset of the first wafer relative to the second wafer. According to the angular offset and positional offset, trigger an adjustment unit to move the second wafer so that the second wafer is aligned with the first wafer.

[0178] The computer-readable storage medium may include: read-only memory (ROM), random access memory (RAM), disk or optical disk, etc.

[0179] Since the computer program stored in the computer-readable storage medium can execute the steps in any of the pre-bonding wafer alignment methods provided in the embodiments of this application, the beneficial effects that any of the pre-bonding wafer 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.

[0180] 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 pre-bonding wafer alignment method described above.

[0181] The above provides a detailed description of a wafer alignment method before bonding 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 alignment method, characterized in that, The method includes: Acquire a first image and at least one second image between two oppositely placed first and second wafers, the first image including an image of a first positioning groove at the edge of the first wafer and an image of a second positioning groove at the edge of the second wafer, and the second image including an image of a portion of the edge of the first wafer and an image of a portion of the edge of the second wafer; In the first image, a first dividing line is determined, which is located between the first positioning groove and the second positioning groove. The first angle information of the groove reference line of the first positioning groove and the second angle information of the groove reference line of the second positioning groove are identified. The groove reference line includes the line connecting the two endpoints of the positioning groove and the outer contour of the wafer. Based on the first angle information, the second angle information, and the second image, the angular offset and position offset of the first wafer relative to the second wafer are determined; Based on the angular offset and the position offset, the adjustment unit is triggered to move the second wafer so that the second wafer is aligned with the first wafer.

2. The method according to claim 1, characterized in that, The identification of the first angle information of the slot reference line of the first positioning slot and the second angle information of the slot reference line of the second positioning slot includes: A first positioning region and a second positioning region are segmented from the first image. The first positioning region is located on one side of the first dividing line and includes the first positioning groove in the image. The second positioning region is located on the other side of the first dividing line and includes the second positioning groove in the image. The first positioning groove and the second positioning groove have symmetrical geometric shapes. The first positioning region and the second positioning region are axially symmetrical about the first dividing line. The bounding box of the positioning area is rotated multiple times, and a target sub-region is selected from multiple sub-regions based on the symmetry score of the sub-regions of the rotated positioning area. The target sub-region includes a slot reference line, which is a line connecting the two endpoints of the positioning slot and the outer contour of the wafer. The rotation angle information of the positioning area to which the target sub-region belongs is determined as the angle information of the slot reference line of the positioning groove, thereby obtaining the first angle information of the slot reference line of the first positioning groove and the second angle information of the slot reference line of the second positioning groove.

3. The method according to claim 2, characterized in that, The process of rotating the bounding box of the positioning region multiple times and filtering the target sub-region from multiple sub-regions based on the symmetry score of the sub-regions of the rotated positioning region includes: 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 regional position information of each candidate sub-region. 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.

4. The method according to claim 3, 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.

5. The method according to claim 4, 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.

6. The method according to claim 5, 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.

7. The method according to claim 5, 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.

8. The method according to claim 7, 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.

9. The method according to claim 3, 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.

10. The method according to claim 9, 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.

11. The method according to claim 10, characterized in that, The step of filtering target sub-regions from the plurality of candidate sub-regions based on the symmetry score includes: The multiple symmetry scores are sorted, and the target sub-region is selected from the multiple candidate sub-regions based on the sorting results.

12. The method according to claim 11, characterized in that, The step of filtering the target sub-region from the plurality of candidate sub-regions according to the sorting results includes: The candidate sub-regions corresponding to symmetry scores greater than the set ranking are identified as the middle sub-regions; 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 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. Candidate subdivision regions containing slot reference lines are selected from the plurality of subdivision regions to obtain the candidate subdivision regions of each of the plurality of rotated intermediate sub-regions, as well as the angle information and region position information of the candidate subdivision regions; 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.

13. The method according to claim 1, characterized in that, The step of determining the angular offset and positional offset of the first wafer relative to the second wafer based on the first angle information, the second angle information, and the second image includes: Construct a third angle information and a first reference line, wherein the third angle information and the second angle information are symmetrical about the first dividing line, and the first reference line is perpendicular to the first dividing line and bisects the first image. Based on the first reference line, the third angle information, and the first angle information, calculate the angular offset of the first wafer relative to the second wafer and the first position offset information; Based on the second image, at least one second position offset information of the first wafer relative to the second wafer is determined; The first position offset information and the second position offset information are fused together to obtain the position offset of the first wafer relative to the second wafer.

14. A wafer alignment apparatus before bonding, characterized in that, include: An image module is used to acquire a first image and at least one second image between two oppositely placed first wafers, the first image including an image of a first positioning groove at the edge of the first wafer and an image of a second positioning groove at the edge of the second wafer, and the second image including an image of a portion of the edge of the first wafer and an image of a portion of the edge of the second wafer; An angle module is used to determine a first dividing line in a first image, the first dividing line being located between the first positioning groove and the second positioning groove, and to identify first angle information of the groove reference line of the first positioning groove and second angle information of the groove reference line of the second positioning groove, the groove reference line including the line connecting the two endpoints of the positioning groove to the outer contour of the wafer. The offset module is used to determine the angular offset and position offset of the first wafer relative to the second wafer based on the first angle information, the second angle information, and the second image. The adjustment module is used to trigger the adjustment unit to move the second wafer according to the angular offset and position offset, so that the second wafer is aligned with the first wafer.

Images