Wafer positioning method and device

Abstract

The invention relates to a wafer positioning method and device. A global image of a standard wafer can be acquired based on a low-magnification lens, and template images of a plurality of target areas in the global image can be acquired based on a high-magnification lens, so that the low-magnification lens and the high-magnification lens are combined to ensure that the template image has a view field range and positioning precision; secondly, target images of all target areas on the corrected wafer are obtained through a high-magnification lens, the initial center positions of all template images in the corresponding target images are determined, and wafer coarse positioning is carried out to achieve the purposes of reducing the search range and adapting errors; performing wafer fine positioning by determining the target center position of each template image in the corresponding search area so as to solve the problem of image angle deviation, and further improving the matching robustness under a complex attitude; and the offset parameter of the corrected wafer is determined based on the target affine transformation matrix, so that wafer positioning with micron-level precision is realized, and a guarantee can be brought to subsequent process operation of the wafer.

Description

Technical Field

[0001] The embodiments in this specification belong to the field of semiconductor manufacturing technology, and in particular relate to a wafer positioning method and apparatus. Background Technology

[0002] Semiconductor wafers can be understood as extremely thin, highly flat, and extremely smooth circular silicon wafers (or other semiconductor materials). They are the basic materials for manufacturing semiconductor devices and integrated circuits (ICs) and can be regarded as the "foundation" of chips.

[0003] In the semiconductor wafer manufacturing process, robotic arms are typically used to perform pick-and-place operations on semiconductor wafers based on methods such as chuck positioning or edge-following positioning. The error range of this wafer positioning method is on the millimeter level. However, subsequent processes such as chip packaging and inspection on semiconductor wafers require extremely high positioning accuracy, needing to control the error to the micrometer level. Current positioning technology mainly relies on single-magnification lenses, which suffers from insufficient accuracy or low efficiency, thus affecting subsequent semiconductor wafer processing operations. Summary of the Invention

[0004] The embodiments of this disclosure provide a wafer positioning method and apparatus.

[0005] In a first aspect of this disclosure, a wafer positioning method is provided. The method includes acquiring a global image of a standard wafer using a low-magnification lens, and acquiring template images corresponding to at least four target regions in the global image using a high-magnification lens, each template image having a corresponding standard center position. The method further includes acquiring target images on a calibration wafer corresponding to each target region using the high-magnification lens, and determining the initial center position of each template image in the corresponding target image. The method also includes determining a search region in the corresponding target image based on the size parameters of each template image and its corresponding initial center position, and determining the target center position of each template image within the corresponding search region. Furthermore, the method includes determining a target affine transformation matrix based on the standard center positions and target center positions corresponding to all template images, and determining an offset parameter for the calibration wafer based on the target affine transformation matrix.

[0006] In a second aspect of this disclosure, a wafer positioning apparatus is provided. The apparatus includes an image acquisition module configured to acquire a global image of a standard wafer using a low-magnification lens, and to acquire template images corresponding to at least four target regions in the global image using a high-magnification lens, each template image having a corresponding standard center position. The apparatus also includes a position determination module configured to acquire target images on the calibration wafer corresponding to each target region using the high-magnification lens, and to determine the initial center position of each template image in the corresponding target image. The apparatus further includes a position calculation module configured to determine a search region in the corresponding target image based on the size parameters of each template image and the corresponding initial center position, and to determine the target center position of each template image within the corresponding search region. Furthermore, the apparatus includes a parameter generation module configured to determine a target affine transformation matrix based on the standard center positions and target center positions corresponding to all template images, and to determine the offset parameters of the calibration wafer based on the target affine transformation matrix.

[0007] In a third aspect of this disclosure, a computer program product is provided, comprising a computer program that is executed by a processor to implement the method according to the first aspect.

[0008] In a fourth aspect of this disclosure, a machine-readable storage medium is provided. The machine-readable storage medium stores machine-executable instructions, which are executed by a processor to implement the method provided according to a first aspect of this disclosure.

[0009] It should be understood that the description in the Summary of the Invention section is not intended to limit the key or essential features of the embodiments of this disclosure, nor is it intended to restrict the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0010] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein:

[0011] Figure 1 A schematic diagram of an example environment in which some embodiments of this disclosure may be implemented is shown;

[0012] Figure 2 A flowchart of a wafer positioning method according to some embodiments of the present disclosure is shown;

[0013] Figure 3 A schematic diagram of a global image with a marked target region is shown, illustrating some embodiments of this disclosure;

[0014] Figure 4A schematic diagram of a global image, labeled with a set of target regions and template regions, is shown, illustrating some embodiments of this disclosure;

[0015] Figure 5 A schematic diagram illustrating a wafer positioning effect according to some embodiments of this disclosure is shown;

[0016] Figure 6 A block diagram of a wafer positioning device according to some embodiments of the present disclosure is shown; and

[0017] Figure 7 A block diagram of an electronic device that can implement several embodiments of the present disclosure is shown. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0019] The terms “comprising” and “having”, and any variations thereof, in this specification, claims, and the foregoing drawings are intended to cover a 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 steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. Depending on the context, the word “if” as it applies herein may be interpreted as “when”, “when”, “in response to determination”, or “in response to detection”.

[0020] As mentioned above, subsequent processes such as chip packaging and inspection on semiconductor wafers require extremely high positioning accuracy, typically needing to control errors within the micrometer range. Current positioning technologies mainly rely on single-magnification lenses, making it difficult to strike a balance between a large field of view and high-precision inspection. For example, while low-magnification lenses can cover a large area of ​​the wafer, insufficient overall resolution can lead to inadequate positioning accuracy. Conversely, while high-magnification lenses can guarantee positioning accuracy to some extent, the limited field of view necessitates multiple shots to obtain a complete wafer image, resulting in low positioning efficiency and consequently impacting subsequent processes such as chip packaging and inspection.

[0021] To address this, embodiments of this disclosure propose a wafer positioning method. The method includes acquiring a global image of a standard wafer using a low-magnification lens, and acquiring template images corresponding to at least four target regions in the global image using a high-magnification lens, each template image having a corresponding standard center position. The method further includes acquiring target images on the calibration wafer corresponding to each target region using the high-magnification lens, and determining the initial center position of each template image in the corresponding target image. The method also includes determining a search region in the corresponding target image based on the size parameters of each template image and its corresponding initial center position, and determining the target center position of each template image within the corresponding search region. Furthermore, the method includes determining a target affine transformation matrix based on the standard center positions and target center positions corresponding to all template images, and determining the offset parameters of the calibration wafer based on the target affine transformation matrix.

[0022] In this way, a global image of a standard wafer can be acquired using a low-magnification lens, and template images corresponding to multiple target regions in the global image can be acquired using a high-magnification lens. This combination of low-magnification and high-magnification lenses ensures that the template images have both a wide field of view and positioning accuracy. Secondly, by determining the initial center position of each template image in the corresponding target image, coarse wafer positioning is performed to reduce the search range and adaptation error. Furthermore, by determining the target center position of each template image in the corresponding search area, fine wafer positioning is performed to address the image angle offset problem, thereby improving the matching robustness under complex postures. Finally, by determining the offset parameters of the corrected wafer based on the target affine transformation matrix, not only is micron-level wafer positioning achieved, but it also provides assurance for subsequent wafer processing operations.

[0023] Figure 1 Schematic diagrams are shown illustrating example environments in which some embodiments of this disclosure can be implemented. For example... Figure 1As shown, the example environment 100 may include a processing terminal 101, which connects to a robotic arm 102 to control the robotic arm 102 to remove the wafer from the cassette. Then, using an edge finder or edge-finding station, the offset angle of the wafer is calculated based on its flat edge or notch to control the robotic arm 102 to perform pose correction on the wafer. Based on the identified outer contour of the wafer, the center position of the wafer is determined, and then, using this center position, the pose-corrected wafer is placed at a designated position on the stage 103 in a relatively horizontal orientation. Here, the robotic arm 102 can remove the wafer from the cassette by clamping or vacuum suction. The wafer in the cassette may be divided into a standard wafer and a correction wafer for subsequent process operations. The correction wafer may be of the same type as the standard wafer. Of course, in the embodiments of this disclosure, the correction wafer may also be a standard wafer; that is, the wafer in the cassette may only contain standard wafers, but this is not a limitation. It is understandable that the process of the processing terminal 101 performing pose correction and center position determination on the wafer, as well as the process of controlling the robotic arm 102 to place the wafer on the stage 103, are all well-known technical means in the art, and will not be elaborated here.

[0024] Furthermore, the processing terminal 101 can also establish connections with the low-magnification lens 104 and the high-magnification lens 105 to control the low-magnification lens 104 to move above the wafer to acquire a global image of the wafer after the robotic arm 102 places the wafer on the stage 103. This global image can be understood as an image containing the entire wafer surface. Based on at least four target regions in the global image, the high-magnification lens 105 is switched to move above the wafer to acquire template images corresponding to each target region. Here, the low-magnification lens 104 and the high-magnification lens 105 can be mounted on the same slide rail structure. The processing terminal 101 can control the low-magnification lens 104 to acquire a global image by adjusting the height of the slide rail structure and the position of the low-magnification lens 104 on the slide rail structure. It can also control the high-magnification lens 105 to acquire multiple template images by adjusting the height of the slide rail structure and the position of the high-magnification lens 105 on the slide rail structure. It is understandable that multiple template regions for positioning are usually etched during the wafer manufacturing process. Each target region in the above global image contains any one of the template regions. The template image corresponding to each target region can be understood as an image containing the template region within the corresponding target region. The size parameters of each target region can be determined based on the magnification of the low-magnification lens 104 (for example, when the magnification of the low-magnification lens 104 is 5X, the size parameters of the target region can be expressed as 6300*12800 pixels so that each target region contains the corresponding complete template region). Furthermore, the diagonal length of the template region in each target region is less than the shortest side of the target region.

[0025] Furthermore, after acquiring the template images captured by the high-magnification lens 105, the processing terminal 101 can control the robotic arm 102 to retrieve the wafer back into the cassette, and then control the robotic arm 102 again to place the wafer (or a calibration wafer for subsequent process operations) at a designated position on the stage 103. The high-magnification lens is then moved above the wafer to acquire target images corresponding to each target area on the wafer. Here, each target image may contain a corresponding target area, and each target area may contain any template area set on the wafer. It is understood that the process by which the processing terminal 101 controls the robotic arm 102 to place the wafer at the designated position on the stage 103 is described above and is a well-known technique in the art, and will not be elaborated further here.

[0026] Furthermore, after acquiring each target image captured by the high-magnification lens 105, the processing terminal 101 can determine the initial center position of each template image in the corresponding target image. Then, based on the size parameters of each template image and the corresponding initial center position, it can determine the search area in the corresponding target image and determine the target center position of each template image in the corresponding search area. Afterward, the processing terminal 101 can also determine the target affine transformation matrix based on the standard center position and target center position corresponding to all template images, and determine the wafer offset parameters based on the target affine transformation matrix. It is understood that the wafer offset parameters may include the rotation angle and translation amount of the wafer on the horizontal plane. The processing terminal 101 can feed back the rotation angle and translation amount of the wafer on the horizontal plane to the PLC control system, so that the PLC control system can drive the stage 103 to achieve the position correction of the wafer. The single fine adjustment amount does not exceed 20um (or it can also be determined according to the stability, accuracy and wafer type of the robotic arm. For example, when the stability of the robotic arm is poor, it can also be set to 100um or more). Of course, the processing terminal 101 in the embodiments of this disclosure can also drive the stage 103 to achieve position correction of the wafer based on the rotation angle and translation amount of the wafer on the horizontal plane, and is not limited thereto.

[0027] In this way, a global image of a standard wafer can be acquired using a low-magnification lens, and template images corresponding to multiple target regions in the global image can be acquired using a high-magnification lens. This combination of low-magnification and high-magnification lenses ensures that the template images have both a wide field of view and positioning accuracy. Secondly, by determining the initial center position of each template image in the corresponding target image, coarse wafer positioning is performed to reduce the search range and adaptation error. Furthermore, by determining the target center position of each template image in the corresponding search area, fine wafer positioning is performed to address the image angle offset problem, thereby improving the matching robustness under complex postures. Finally, by determining the offset parameters of the corrected wafer based on the target affine transformation matrix, not only is micron-level wafer positioning achieved, but it also provides assurance for subsequent wafer processing operations.

[0028] It should be understood that the architecture and functionality in example environment 100 are described for illustrative purposes only and do not imply any limitation on the scope of this disclosure. Embodiments of this disclosure can also be applied to other environments with different architectures and / or functionalities.

[0029] Figure 2 A flowchart of a wafer positioning method according to some embodiments of the present disclosure is shown. Method 200 may be, for example, by... Figure 1 The processing terminal in the example environment shown executes. For example... Figure 2 As shown in block 202, method 200 can acquire a global image of the standard wafer based on a low-magnification lens, and acquire template images corresponding to at least four target regions in the global image based on a high-magnification lens. In some implementations, the processing terminal can control a robotic arm to remove the standard wafer from the cassette, and then use an edge finder or edge finding station to calculate the wafer offset angle based on the flat edge or notch of the standard wafer, so as to control the robotic arm to perform pose correction on the standard wafer, and determine the center position of the standard wafer based on the identified outer contour of the standard wafer, and then place the pose-corrected standard wafer in a relatively horizontal posture at a designated position on the stage, based on the center position of the standard wafer.

[0030] Subsequently, the processing terminal can control the low-magnification lens to move above the standard wafer to acquire a global image of the standard wafer. This global image can be understood as an image encompassing the entire surface of the standard wafer. At least four target regions are marked within this global image. Then, the high-magnification lens is switched to move above the standard wafer to acquire a template image corresponding to each target region based on its location. Here, each target region in the global image includes any template region set on the standard wafer. The template image corresponding to each target region can be understood as an image containing the template region within the corresponding target region. The size parameters of each target region can be determined based on the magnification of the low-magnification lens, and the diagonal length of the template region in each target region is less than the shortest side of the target region.

[0031] In some implementations, when the processing terminal acquires template images corresponding to at least four target regions in a global image based on a high-magnification lens, it can mark at least four target regions in the global image. Each target region includes any template region disposed on a standard wafer. In one example, four template regions located at different orientations can be identified in the global image based on an image recognition algorithm. Then, the center position of these four template regions is used as the center position of the corresponding target region. Combined with the target region size parameters determined by the magnification of the low-magnification lens (e.g., different magnifications have corresponding region size parameter correspondences), the corresponding four target regions are marked in the global image (or the template regions within each target region can also be marked simultaneously).

[0032] Please see Figure 3 The illustration shows a schematic diagram of a global image with a marked target region according to some embodiments of the present disclosure. For example... Figure 3 As shown, the global image 300 contains four target regions. Each target region is marked by a rectangle with the same size parameters. Each target region contains any template region set on a standard wafer. Furthermore, within each target region, the corresponding template region can also be marked by a rectangle with the same size parameters.

[0033] In addition, please see Figure 4 The illustration shows a global image diagram with a set of target regions and template regions marked according to some embodiments of the present disclosure. For example... Figure 4 As shown, the target region in the global image 400 can be marked with a larger rectangle, and the corresponding template region can be marked with a smaller rectangle. It can be seen that the template region is within the target region, and the template image mentioned in the embodiments of this disclosure can be understood as an image containing the template region, and the target image mentioned can be understood as an image containing the target region.

[0034] Of course, embodiments of this disclosure may also allow operators to mark at least four target regions within the global image and template regions within each target region, and are not limited thereto.

[0035] Subsequently, the processing terminal can acquire template images corresponding to each template region in the global image using a high-magnification lens. In one example, the high-magnification lens can be moved above the standard wafer, and template images corresponding to the respective template regions can be acquired based on the location of each target region, so that each template image contains the corresponding complete template region. Furthermore, after acquiring the template images corresponding to each template region, the processing terminal can also determine the physical coordinates of the center of each template image in the Cartesian coordinate system established based on the center pixel coordinates of each template image and the Cartesian coordinate system established based on the platform, i.e., the standard center position of each template image. Here, the Cartesian coordinate system established based on the platform can be understood as a Cartesian coordinate system established with the platform center as the origin, the horizontal direction to the right of the platform center as the horizontal axis, and the vertical direction upward of the platform center as the vertical axis. The processing terminal can use a nine-point calibration algorithm to determine the transformation matrix between the pixel coordinates on the template image acquired by the high-magnification lens and the physical coordinates in the Cartesian coordinate system, and calculate the standard center position of each template image based on this transformation matrix and the center pixel coordinates of each template image. It is understood that the process of determining the transformation matrix through the nine-point calibration algorithm is a well-known technique in the art. Of course, the method of determining the standard center position of each template image in the embodiments of this disclosure can also adopt other well-known techniques in the art, but will not be elaborated here.

[0036] Furthermore, after acquiring the template images corresponding to each template region, the processing terminal can also determine the pixel equivalent of the corresponding template image based on the size parameters of each template image and the resolution of the high-magnification lens at the current magnification (the high-magnification lens has corresponding resolutions at different magnifications). Here, the size parameters of the template image may include width and height. The pixel equivalent of the template image in the horizontal direction is determined by calculating the ratio of the width of the template image to the number of pixels corresponding to the horizontal direction in the resolution of the high-magnification lens at the current magnification; and the pixel equivalent of the template image in the vertical direction can also be determined by calculating the ratio of the height of the template image to the number of pixels corresponding to the vertical direction in the resolution of the high-magnification lens at the current magnification, but this is not limited to these methods.

[0037] In block 204, method 200 can acquire target images corresponding to each target region on the calibration wafer using a high-magnification lens, and determine the initial center position of each template image in the corresponding target image. In some implementations, the processing terminal can control a robotic arm to retrieve a standard wafer back into the cassette, and then control the robotic arm to remove the calibration wafer (or standard wafer) for subsequent process operations from the cassette and place it at a designated position on the stage. By controlling the high-magnification lens to move above the standard wafer, and acquiring target images corresponding to each target region based on the location and size parameters of each target region, each target image contains the corresponding complete target region and the template region within the complete target region. Here, the location of each target region can be understood as the physical coordinates of the center of each template image in a Cartesian coordinate system, as mentioned above, so as to facilitate the control of the high-magnification lens to quickly find each target region above the calibration wafer, thereby improving the acquisition efficiency of each target image. It is understood that the process of the processing terminal controlling the robotic arm to place the calibration wafer at a designated position on the stage can be referred to the above and is a well-known technique in the art, and will not be elaborated further here.

[0038] It should be noted that since the calibration wafer and the standard wafer are the same type of wafer (or the calibration wafer is the same as the standard wafer), the template region contained in each target image is exactly the same as the template region contained in the corresponding template image, so as to ensure the accuracy of the offset parameters of the subsequent calibration wafer.

[0039] In some implementations, when determining the initial center position of each template image in the corresponding target image, the processing terminal can determine whether the pixel equivalent of each template image is consistent with the pixel equivalent of the corresponding target image based on the pixel equivalent of each template image and the pixel equivalent of the corresponding target image. Here, the process for determining the pixel equivalent of the target image can refer to the above, for example, by calculating the ratio of the width of the target image to the number of pixels corresponding to the horizontal direction in the resolution at the corresponding magnification when acquiring the target image by a high-magnification lens; and, it can also be determined by calculating the ratio of the height of the target image to the number of pixels corresponding to the vertical direction in the resolution at the corresponding magnification when acquiring the target image by a high-magnification lens, and is not limited to this.

[0040] It is understandable that when the pixel equivalent in the horizontal direction of each template image is inconsistent with the pixel equivalent in the horizontal direction of the corresponding target image, or when the pixel equivalent in the vertical direction of each template image is inconsistent with the pixel equivalent in the vertical direction of the corresponding target image, it indicates that the pixel equivalent in each template image is inconsistent with the pixel equivalent in the corresponding target image. When the pixel equivalent in the horizontal direction of each template image is consistent with the pixel equivalent in the horizontal direction of the corresponding target image, and the pixel equivalent in the vertical direction is consistent with the pixel equivalent in the vertical direction of the corresponding target image, it indicates that the pixel equivalent in each template image is consistent with the pixel equivalent in the corresponding target image.

[0041] Subsequently, in response to determining that the pixel equivalent of each template image is inconsistent with the pixel equivalent of the corresponding target image, the processing terminal can scale the corresponding template images based on the pixel equivalent of each target image to ensure that the scaled template images and the matching targets (i.e., template regions) in the corresponding target images are consistent in size parameters. For example, if the pixel equivalent of each template image in the horizontal direction is smaller than that in the horizontal direction of the corresponding target image, and the pixel equivalent in the vertical direction is smaller than that in the vertical direction of the corresponding target image, the corresponding template images can be enlarged based on the pixel equivalents in the horizontal and vertical directions of the target image. This ensures that the pixel equivalents in the horizontal direction of the enlarged template images are consistent with those in the horizontal direction of the corresponding target image, and the pixel equivalents in the vertical direction are consistent with those in the vertical direction of the corresponding target image.

[0042] Subsequently, the processing terminal can downsample the scaled template images and corresponding target images, and then process them using a template matching algorithm to determine the initial center position of each template image within the corresponding target image. It is understandable that, due to the high resolution of the template and target images, directly processing them would easily lead to excessive resource consumption. Therefore, downsampling the scaled template and target images is performed to determine the approximate position of each template image within the corresponding target image during the wafer coarse positioning stage. Here, downsampling the scaled template and target images can be understood as fusing pixels in the template and target images using a linear interpolation algorithm. This process is a well-known technique in the field and will not be elaborated upon further.

[0043] Furthermore, the template matching algorithm processes the downsampled template images and corresponding target images. This can be understood as sliding the downsampled template images onto the corresponding target images multiple times in a left-to-right and top-to-bottom order. Then, based on the position of the center of each template image on the corresponding target image after each sliding process (i.e., the pixel coordinates of the center of each template image on the corresponding target image), the matching degree between the template image and the corresponding target image at each position is calculated. The matching degree matrix is ​​constructed to statistically analyze the matching degree at multiple positions, and the position corresponding to the maximum matching degree is determined as the initial center position of each template image in the corresponding target image. Here, calculating the matching degree between the template image and the corresponding target image at each position can be understood as performing normalization processing on the template image and the corresponding target image at each position respectively, then identifying the overlapping area between the normalized template image and the corresponding target image, and calculating the matching degree based on the pixel values ​​of multiple positions of the normalized template image in the overlapping area and the pixel values ​​of multiple corresponding positions of the corresponding target image in the overlapping area. The processing method is a well-known technique in this field, and will not be elaborated here.

[0044] In box 206, method 200 can determine a search region in a corresponding target image based on the size parameters of each template image and its corresponding initial center position, and determine the target center position of each template image within the corresponding search region. In some implementations, when the processing terminal determines the search region in a corresponding target image based on the size parameters of each template image and its corresponding initial center position, it can determine the size parameters of the corresponding search region based on the size parameters of each template image and a preset extended size parameter. It is understood that the size parameters of each template image include width and height, the preset extended size parameter includes a preset extended width and a preset extended height, and the size parameters of the search region corresponding to each template image include the width and height of the search region. In one example, the width of the search region corresponding to each template image can be the sum of the width of each template image and the preset extended width, and the height of the search region corresponding to each template image can be the sum of the height of each template image and the preset extended height. This method can effectively reduce the computational load, thereby improving wafer positioning efficiency.

[0045] Subsequently, the processing terminal can determine the search region in the corresponding target image based on the initial center position corresponding to each template image and the size parameters of the corresponding search region. In one example, the initial center position corresponding to the template image can be identified in each target image as the center position of the corresponding search region. Based on the size parameters and center position of the corresponding search region, the search region is determined in the target image such that the distance between each wide side of the search region and the center position is half the height in the size parameters, and the straight-line distance between each high side of the search region and the center position is half the width in the size parameters.

[0046] In some implementations, when determining the target center position of each template image in the corresponding search area, the processing terminal can rotate each template image based on a preset rotation angle to obtain at least two rotated images corresponding to each template image. Here, the preset rotation angle can be understood as multiple rotation angles determined based on an angle range of -10 degrees to 10 degrees and a step size of 0.5 degrees. By keeping the center position of each template image unchanged, each template image is rotated according to each rotation angle to obtain a rotated image of each template image at each rotation angle.

[0047] Subsequently, the processing terminal can determine the search image of the corresponding search region in each target image, and process the rotated images and search images corresponding to each template image based on the template matching algorithm to obtain the center pixel position of each template image in the corresponding search region. In one example, the search region in each target image can be cropped to obtain the search image of the corresponding search region. When processing the rotated images and search images corresponding to each template image based on the template matching algorithm, the rotated images corresponding to each template image are slid multiple times on the corresponding search image in a left-to-right and top-to-bottom order. Then, based on the position of the center of each rotated image on the corresponding search image after each sliding process (i.e., the pixel coordinates of the center of each rotated image on the corresponding search image), the matching degree between the rotated image and the corresponding search image at each position is calculated, so as to count the matching degree corresponding to multiple positions by constructing a matching degree matrix. Then, after obtaining the matching degree matrix between each rotated image and the corresponding search image corresponding to each template image, the position corresponding to the maximum matching degree in all matching degree matrices is determined as the center pixel position of each template image in the corresponding search region. Here, calculating the matching degree between the rotated image corresponding to each position and the corresponding search image can be understood as performing normalization processing on the rotated image corresponding to each position and the corresponding search image respectively, then identifying the overlapping area between each normalized rotated image and the corresponding search image, and calculating the matching degree based on the pixel values ​​of multiple positions in the overlapping area of ​​each normalized rotated image and the pixel values ​​of multiple corresponding positions in the overlapping area of ​​the corresponding search image. The processing method is a well-known technique in this field, and will not be elaborated here.

[0048] Of course, embodiments of this disclosure may also be implemented without rotating each template image based on a preset rotation angle; that is, the preset rotation angle may be set to 0. In one example, the processing terminal may also determine the search image for the corresponding search region in each target image, and directly process each template image and the search image based on a template matching algorithm to obtain the center pixel position of each template image in the corresponding search region. Here, the process of determining the center pixel position of each template image in the corresponding search region can be referred to the above, and will not be elaborated further.

[0049] Subsequently, the processing terminal can perform transformation processing on the center pixel position of the corresponding template image based on the pixel equivalent and vertex position of each target image, so as to obtain the target center position of each template image in the corresponding search area, that is, the pixel position of the center of each template image in the corresponding search area, and the physical coordinates in the Cartesian coordinate system corresponding to the platform. Here, the vertex position of each target image can be understood as the physical coordinates of the top-left vertex (or other vertices, not limited to this) of each target image in the Cartesian coordinate system corresponding to the platform. It can be determined based on the physical coordinates of the center of the corresponding target image in the Cartesian coordinate system corresponding to the platform, the pixel size of the corresponding target image, and the pixel equivalent. For example, if the vertex position of each target image is represented as (left_physical, top_physical), the physical coordinates of the center of the corresponding target image in the Cartesian coordinate system corresponding to the platform are represented as (x_center_physical, y_center_physical), the pixel size of the corresponding target image includes pixel width and pixel height, and the pixel equivalent of the corresponding target image includes the pixel equivalent in the horizontal direction and the pixel equivalent in the vertical direction, the vertex position of each target image can be determined using the following expression:

[0050] left_physical = x_center_physical - pixel width * 0.5 * equivalent pixel value in the horizontal direction

[0051] top_physical = y_center_physical + pixel height * 0.5 * pixel equivalent in the vertical direction

[0052] It is understandable that the physical coordinates of the center of each target image in the Cartesian coordinate system corresponding to the stage can be determined when acquiring the target image corresponding to each target area on the calibration wafer based on the high-magnification lens. Of course, it can also be obtained using techniques well known in the art, but we will not go into details here.

[0053] In one example, assuming the pixel equivalent of each target image is represented as including the pixel equivalent in the horizontal direction and the pixel equivalent in the vertical direction, the vertex position of each target image is represented as (left_physical, top_physical), the center pixel position of each template image is represented as (u, v), and the target center position of each template image in the corresponding search area is represented as (x, y), the target center position of each template image in the corresponding search area can be determined by the following expression:

[0054] x = left_physical + u * pixel equivalent in the horizontal direction

[0055] y = top_physical - v * pixel equivalent in the vertical direction

[0056] In block 208, method 200 can determine the target affine transformation matrix based on the standard center positions and target center positions corresponding to all template images, and determine the offset parameters of the correction wafer based on the target affine transformation matrix. In some implementations, when the processing terminal determines the target affine transformation matrix based on the standard center positions and target center positions corresponding to all the template images, it can determine at least two computational position sets and a verification position set corresponding to each computational position set based on the standard center positions corresponding to all the template images. Each computational position set has at least three standard center positions and target center positions corresponding to the template images, and each verification position set has one standard center position and target center position corresponding to one template image. In one example, taking four template images as an example, four computational position sets and a verification position set corresponding to each computational position set can be determined by combining all the template images. Each computational position set includes the standard center positions and target center positions corresponding to any three template images, and the verification position set corresponding to each computational position set includes the standard center position and target center position corresponding to the remaining template image.

[0057] Subsequently, the processing terminal can construct corresponding initial affine transformation matrices based on each computational location set, and determine the corresponding deviation values ​​based on the verification location set and the initial affine transformation matrix corresponding to each computational location set. In one example, the standard center position and target center position corresponding to each template image in each computational location set can be substituted into a preset matrix parameter calculation expression. The unsolved matrix parameters of the affine transformation matrix in the preset matrix parameter calculation expression are then calculated using the least squares method. The affine transformation matrix substituted into the matrix parameters is then used as the initial affine transformation matrix corresponding to each computational location set. The preset matrix parameter calculation expression can be found as shown below:

[0058]

[0059] In the above expression, ( , ) can be the center position of the target corresponding to the template image, ( , ) can be the standard center position corresponding to the template image, and a, b, c, d, e and f can be the matrix parameters to be solved for the affine transformation matrix.

[0060] After obtaining the initial affine transformation matrix corresponding to each computational position set, the standard center position and the corresponding initial affine transformation matrix of the verification position set corresponding to each computational position set can be substituted into the aforementioned preset matrix parameter calculation expression to obtain the actual center position. The deviation between this actual center position and the target center position in the verification position set is then calculated, and this error value is used as the deviation value corresponding to the corresponding computational position set. Here, the deviation between the actual center position and the target center position in the verification position set can be calculated using the following expression:

[0061] Diff = max(| x - x'|, | y - y'|)

[0062] In the above expression, Diff can be the deviation between the actual center position and the target center position in the verification position set, max() can be the maximum value, (x, y) can be the target center position in the verification position set, and (x', y') can be the actual center position.

[0063] It is understandable that when the deviation value corresponding to a certain set of calculated positions exceeds a preset deviation threshold, it indicates that the initial affine transformation matrix corresponding to that set of calculated positions is invalid; when the deviation value corresponding to a certain set of calculated positions does not exceed the preset deviation threshold, it indicates that the initial affine transformation matrix corresponding to that set of calculated positions is valid.

[0064] Subsequently, in response to determining that the deviation value corresponding to each calculation position set does not exceed a preset deviation threshold, the processing terminal can determine the mean calculation result of all initial affine transformation matrices as the target affine transformation matrix. It is understood that the matrix parameters at each position in the target affine transformation matrix can be the mean calculation result of the matrix parameters at the corresponding positions in all initial affine transformation matrices. Furthermore, in embodiments of this disclosure, when it is determined that only one calculation position set has a deviation value that does not exceed the preset deviation threshold, the initial affine transformation matrix corresponding to that calculation position set can be directly used as the target affine transformation matrix.

[0065] In some implementations, when determining the offset parameters of the correction wafer based on the target affine transformation matrix, the processing terminal can determine the target rotation angle based on the matrix parameters located at a preset first position in the target affine transformation matrix. Here, the preset first position can be understood as the first column of the first row and the first column of the second row in the target affine transformation matrix. In one example, the target rotation angle is calculated by substituting the matrix parameters located at the preset first position in the target affine transformation matrix into the expression described below:

[0066] θ = arctan2 (d, a)

[0067] In the above formula, θ can be the target rotation angle, and a and d can be the matrix parameters in the target affine transformation matrix that are located in the preset first position (a can be the matrix parameter in the first row and first column of the target affine transformation matrix, and d can be the matrix parameter in the second row and first column of the target affine transformation matrix).

[0068] Subsequently, the processing terminal can determine the translation amount based on the matrix parameters located at a preset second position in the target affine transformation matrix, and determine the target rotation angle and translation amount as the offset parameters for correcting the wafer. Here, the preset second position can be understood as the third column of the first row and the third column of the second row in the target affine transformation matrix, and the translation amount can be understood as the offset in the horizontal direction and the translation in the vertical direction. The offset in the horizontal direction is the matrix parameter located at the third column of the first row in the target affine transformation matrix, and the offset in the vertical direction is the matrix parameter located at the third column of the second row in the target affine transformation matrix.

[0069] It is understood that after determining the offset parameters of the calibration wafer, the processing terminal can also feed back these offset parameters to the PLC control system, so that the PLC control system can drive the stage to correct the position of the calibration wafer, ensuring that the position of the calibration wafer after correction is consistent with that of the standard wafer on the stage, and that the single fine adjustment amount does not exceed 20µm (or it can be determined according to the stability, accuracy and wafer type of the robotic arm; for example, when the stability of the robotic arm is poor, it can be set to 100µm or more). Of course, the processing terminal of the embodiments of this disclosure can also directly drive the stage to correct the position of the calibration wafer based on the offset parameters of the calibration wafer, and is not limited thereto.

[0070] Of course, after performing position correction processing on the correction wafer based on the offset parameters of the correction wafer in the embodiments of this disclosure, the correction wafer after position correction can also be repositioned for verification. For example, the high-magnification lens can be controlled again to acquire target images corresponding to each target region on the correction wafer after position correction, and the deviation values ​​corresponding to each calculated position set can be recalculated with reference to the above steps. It can be understood that when the deviation values ​​corresponding to each calculated position set recalculated do not exceed the preset deviation threshold, it indicates that the correction wafer has completed position correction; when the deviation values ​​corresponding to one or more calculated position sets recalculated still exceed the preset deviation threshold, it indicates that the correction wafer has not yet completed position correction, and the offset parameters of the correction wafer can be recalculated with reference to the above steps until the correction wafer completes position correction.

[0071] Please see Figure 5 A schematic diagram illustrating a wafer positioning effect according to some embodiments of the present disclosure is shown. Figure 5As shown in Figure 5A, a superimposed image of the standard wafer and the calibration wafer without position correction is displayed. It can be seen that ghosting occurs in the superimposed image, meaning that the calibration wafer without position correction is not in the same position as the standard wafer on the stage. Figure 5B, a superimposed image of the standard wafer and the calibration wafer after position correction is displayed. It can be seen that no ghosting occurs in the superimposed image, meaning that the calibration wafer after position correction is in the same position as the standard wafer on the stage.

[0072] Figure 6 A block diagram of a wafer positioning apparatus according to some embodiments of the present disclosure is shown. The various embodiments in this specification are described in a progressive manner, with reference to each other for similar or identical parts. Each embodiment focuses on describing the differences from other embodiments. In particular, the apparatus embodiments are basically similar to the method embodiments, so the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. Figure 6 As shown, the wafer positioning device 600 includes an image acquisition module 602, configured to acquire a global image of a standard wafer using a low-magnification lens, and to acquire template images corresponding to at least four target regions in the global image using a high-magnification lens, each template image having a corresponding standard center position. The wafer positioning device 600 also includes a position determination module 604, configured to acquire target images corresponding to each target region on the correction wafer using a high-magnification lens, and to determine the initial center position of each template image in the corresponding target image. The wafer positioning device 600 also includes a position calculation module 606, configured to determine a search region in the corresponding target image based on the size parameters of each template image and the corresponding initial center position, and to determine the target center position of each template image within the corresponding search region. Furthermore, the wafer positioning device 600 also includes a parameter generation module 608, configured to determine a target affine transformation matrix based on the standard center positions and target center positions corresponding to all template images, and to determine the offset parameters of the correction wafer based on the target affine transformation matrix.

[0073] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this specification are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in or transmitted through a computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., Digital Versatile Discs (DVDs)), or semiconductor media (e.g., Solid State Disks (SSDs)).

[0074] Figure 7 Block diagrams of electronic devices that can implement various embodiments of the present disclosure are shown. For example... Figure 7 As shown, the electronic device 700 includes a processor 701, which can perform various appropriate actions and processes based on computer program instructions loaded into random access memory (RAM) 703 according to computer program instructions stored in read-only memory (ROM) 702. The RAM 703 may also store various programs and data required for the operation of the electronic device 700. The processor 701, ROM 702, and RAM 703 are interconnected via a bus 704. An input / output (I / O) interface 705 is also connected to the bus 704.

[0075] The various processes and procedures described above, such as method 200, can be executed by processor 701. For example, in some embodiments, method 200 may be implemented as a software program tangibly contained in a machine-readable medium. In some embodiments, part or all of the software program may be loaded into and / or installed onto electronic device 700 via ROM 702. When the software program is loaded into RAM 703 and executed by processor 701, one or more actions of method 200 described above may be performed.

[0076] The functions described above in this document can be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload programmable logic devices (CPLDs), and so on.

[0077] The program code used to implement the methods of this disclosure may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a standalone software package partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0078] This disclosure can be a method, apparatus, system, and / or program product. The program product may include a machine-readable storage medium on which machine-readable program instructions for performing various aspects of this disclosure are loaded. The machine-readable program instructions described herein can be downloaded from the machine-readable storage medium to various computing / processing devices, or downloaded via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the machine-readable program instructions from the network and forwards them to the machine-readable storage medium in the respective computing / processing device.

[0079] Machine program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. Machine-readable program instructions may be executed entirely on a user's computer, partially on a user's computer, as a standalone software package, partially on a user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing state information from the machine-readable program instructions to implement various aspects of this disclosure.

[0080] In the context of this disclosure, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. Furthermore, although operations are depicted in a specific order, this should be understood as requiring that such operations be performed in the specific order shown or in sequential order, or requiring that all illustrated operations be performed to achieve the desired result. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the foregoing discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations.

[0081] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A wafer positioning method, characterized in that, include: A global image of a standard wafer is acquired using a low-magnification lens, and template images corresponding to at least four target regions in the global image are acquired using a high-magnification lens. Each template image has a corresponding standard center position. Based on the high-magnification lens, target images corresponding to each target region on the calibration wafer are acquired, and the initial center position of each template image in the corresponding target image is determined; Based on the size parameters of each template image and the corresponding initial center position, a search area is determined in the corresponding target image, and the target center position of each template image in the corresponding search area is determined. as well as Based on the standard center position and the target center position corresponding to all the template images, the target affine transformation matrix is ​​determined, and the offset parameter of the correction wafer is determined based on the target affine transformation matrix.

2. The method according to claim 1, characterized in that, The step of acquiring template images corresponding to at least four target regions in the global image based on a high-magnification lens includes: At least four target regions are marked in the global image, each target region having a corresponding template region; and The template images corresponding to each template region in the global image are obtained using a high-magnification lens.

3. The method according to claim 1, characterized in that, Determining the initial center position of each template image in the corresponding target image includes: Based on the pixel equivalent of each template image and the pixel equivalent of the corresponding target image, determine whether the pixel equivalent of each template image is consistent with the pixel equivalent of the corresponding target image; In response to determining that the pixel equivalent of each of the template images is inconsistent with the pixel equivalent of the corresponding target image, the corresponding template image is scaled based on the pixel equivalent of each of the target images; and The scaled template images and corresponding target images are downsampled, and the downsampled template images and corresponding target images are processed based on a template matching algorithm to determine the initial center position of each template image in the corresponding target image.

4. The method according to claim 1, characterized in that, The step of determining the search region in the corresponding target image based on the size parameters of each template image and the corresponding initial center position includes: Based on the size parameters of each template image and the preset extended size parameters, the size parameters of the corresponding search area are determined; and Based on the initial center position corresponding to each template image and the size parameters of the corresponding search region, a search region is determined in the corresponding target image.

5. The method according to claim 4, characterized in that, Determining the target center position of each template image in the corresponding search area includes: The template images are rotated based on a preset rotation angle to obtain at least two rotated images corresponding to each template image; In each of the target images, a search image corresponding to the search region is determined, and based on a template matching algorithm, each of the rotated images corresponding to each template image and the search image are processed to obtain the center pixel position of each template image in the corresponding search region; and Based on the pixel equivalent and vertex position of each target image, the center pixel position corresponding to the template image is transformed to obtain the target center position of each template image in the corresponding search area.

6. The method according to any one of claims 1-5, characterized in that, The step of determining the target affine transformation matrix based on the standard center position and the target center position corresponding to all the template images includes: Based on the standard center positions corresponding to all the template images, at least two sets of calculated positions and a set of verified positions corresponding to each set of calculated positions are determined. Each set of calculated positions has at least three standard center positions and target center positions corresponding to the template images. Each set of verified positions has one standard center position and one target center position corresponding to the template image. Construct corresponding initial affine transformation matrices based on each set of computational locations, and determine corresponding deviation values ​​based on the verification location set corresponding to each set of computational locations and the initial affine transformation matrices. Determine whether the deviation value corresponding to each of the calculated location sets exceeds a preset deviation threshold; and In response to determining that the deviation value corresponding to each of the calculated position sets does not exceed the preset deviation threshold, the mean calculation result of all the initial affine transformation matrices is determined as the target affine transformation matrix.

7. The method according to claim 6, characterized in that, Determining the offset parameters of the calibration wafer based on the target affine transformation matrix includes: The target rotation angle is determined based on the matrix parameters at a preset first position in the target affine transformation matrix; and The translation amount is determined based on the matrix parameters at the preset second position in the target affine transformation matrix, and the target rotation angle and the translation amount are determined as the offset parameters of the correction wafer.

8. A wafer positioning device, characterized in that, include: The image acquisition module is configured to acquire a global image of a standard wafer based on a low-magnification lens, and to acquire template images corresponding to at least four target regions in the global image based on a high-magnification lens, each template image having a corresponding standard center position; The position determination module is configured to acquire target images corresponding to each target region on the calibration wafer based on the high-magnification lens, and determine the initial center position of each template image in the corresponding target image; The position calculation module is configured to determine a search area in the corresponding target image based on the size parameters of each template image and the corresponding initial center position, and to determine the target center position of each template image in the corresponding search area; as well as The parameter generation module is configured to determine the target affine transformation matrix based on the standard center position and the target center position corresponding to all the template images, and to determine the offset parameters of the calibration wafer based on the target affine transformation matrix.

9. A computer-readable storage medium having a computer program stored thereon, the computer-readable storage medium storing instructions that, when executed on a computer or processor, cause the computer or processor to perform the steps of the method as claimed in any one of claims 1-7.

10. An electronic device, characterized in that, include: One or more processors, and A memory associated with the one or more processors, the memory being used to store program instructions that, when read and executed by the one or more processors, perform the steps of the method according to any one of claims 1-7.

Images