Wafer alignment method and related device
By identifying the target area on the wafer for image acquisition and least squares fitting, the problem of rapid and accurate alignment for wafer notch angle identification is solved, realizing an efficient wafer alignment method and device.
Patent Information
- Application Number
- CN202511788744.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-02-27
AI Technical Summary
In the semiconductor manufacturing process, existing technologies face challenges such as high computational load, insufficient robustness, and inadequate positioning accuracy in quickly and accurately identifying the angle of wafer notches and achieving alignment.
The target area is determined based on the wafer center position and the preset orientation of the notch. Image acquisition is performed and the notch edge point set is fitted using the least squares method to obtain a quadratic fitting curve. The offset and deviation angle are then calculated to achieve alignment.
It reduces image acquisition costs, improves acquisition efficiency, achieves sub-micron level positioning accuracy and fast and accurate wafer alignment, adapts to notch images under different process conditions, and has strong robustness.
Smart Images
Figure CN121586435A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of wafer detection, and particularly relates to a wafer alignment method and related device. BACKGROUND
[0002] In a semiconductor manufacturing process, a wafer is a substrate material for photolithography, etching, deposition and other processes. The wafer is usually a circular silicon wafer. In order to facilitate the correct alignment of the wafer in the manufacturing equipment, a notch is pre-fabricated on the edge of the wafer as a reference for crystal orientation and processing positioning. In advanced processes, the wafer size has reached 12 inches (diameter 300 mm), and the process alignment accuracy requirement is usually in the micron or even sub-micron level. Therefore, how to quickly and accurately identify the angle of the notch and align the wafer through the notch has become a technical problem to be solved. SUMMARY
[0003] Therefore, the purpose of the present application is to provide a wafer alignment method and related device, which can accurately calculate the deviation angle of the notch and quickly and accurately align the wafer through the notch. The specific scheme is as follows:
[0004] In one aspect, the present application provides a wafer alignment method, comprising:
[0005] determining a target area in which the notch is located in the wafer based on a center position of the wafer and a preset orientation of the notch in the wafer;
[0006] performing image acquisition on the target area to obtain a target image of the target area;
[0007] performing curve fitting on a notch edge point set in the target image by using a least square method to obtain a quadratic fitting curve, the notch edge point set comprising a plurality of edge points located on the edge of the notch;
[0008] determining an offset amount of a vertex position of the quadratic fitting curve from a preset position of the notch in the target image based on the vertex position and the preset position, the vertex position being an actual position of the notch in the target image, and the preset position being a preset position of the notch when reaching the preset orientation;
[0009] determining a deviation angle of the notch from the preset orientation based on the offset amount and a radius of the wafer, and aligning the notch according to the deviation angle so that the orientation of the notch conforms to the preset orientation.
[0010] Optionally, the determining the offset of the vertex position from the preset position based on the vertex position of the vertex on the quadratic fitting curve in the target image and the preset position of the notch in the target image comprises:
[0011] determining a center position of the target image, the center position being a preset position of the notch when reaching the preset orientation;
[0012] determining the offset of the vertex position from the center position based on the vertex position of the vertex on the quadratic fitting curve in the target image and the center position of the target image.
[0013] Optionally, when the orientation of the notch in the target image is downward or upward, the determining the center position of the target image comprises:
[0014] determining a horizontal coordinate of the center of the target image based on a horizontal dimension of the target image;
[0015] the determining the offset of the vertex position from the center position based on the vertex position of the vertex on the quadratic fitting curve in the target image and the center position of the target image comprises:
[0016] determining the offset of the vertex position from the center position based on a horizontal coordinate of the vertex on the quadratic fitting curve in the target image and the horizontal coordinate of the center of the target image.
[0017] Optionally, when the orientation of the notch in the target image is leftward or rightward, the determining the center position of the target image comprises:
[0018] determining a vertical coordinate of the center of the target image based on a vertical dimension of the target image;
[0019] the determining the offset of the vertex position from the center position based on the vertex position of the vertex on the quadratic fitting curve in the target image and the center position of the target image comprises:
[0020] determining the offset of the vertex position from the center position based on a vertical coordinate of the vertex on the quadratic fitting curve in the target image and the vertical coordinate of the center of the target image.
[0021] Optionally, before the fitting the set of edge points of the notch in the target image by the least square method to obtain the quadratic fitting curve, the method further comprises:
[0022] performing edge detection on the target image to obtain an initial edge point set in the target image, the initial edge point set including a plurality of edge points located on the notch edge and edge points located on other regions of the wafer except the notch;
[0023] performing curve fitting on the initial edge point set in the target image by the least square method to obtain the quadratic fitting curve.
[0024] performing curve fitting on the initial edge point set in the target image by the least square method to obtain the quadratic fitting curve.
[0025] Optionally, the performing curve fitting on the initial edge point set in the target image by the least square method to obtain the quadratic fitting curve includes:
[0026] if the quadratic fitting curve does not meet the curve requirement, performing region of interest screening processing on the initial edge point set to obtain the notch edge point set;
[0027] performing curve fitting on the initial edge point set in the target image by the least square method to obtain the quadratic fitting curve.
[0028] Optionally, before the performing edge detection on the target image to obtain the initial edge point set in the target image, the method further includes:
[0029] performing gray scale normalization processing, filtering and noise reduction processing, and edge enhancement processing on the target image.
[0030] Optionally, in the curve fitting process, the edge points in the notch edge point set are subjected to outlier removal processing by a random sample consensus algorithm to obtain the quadratic fitting curve meeting a preset accuracy requirement.
[0031] Optionally, when the proportion of the notch depth relative to the radius of the wafer is less than a preset proportion, the determining the deviation angle of the notch from the preset orientation based on the offset and the radius of the wafer includes:
[0032] determining the offset as an arc length between the notch and the preset orientation;
[0033] determining the deviation angle of the notch from the preset orientation based on a ratio of the arc length to the radius of the wafer.
[0034] In another aspect, the embodiments of the present application also provide a wafer alignment device, including:
[0035] The first determining unit is configured to determine a target area in which the gap is located in the wafer based on a center position of the wafer and a preset orientation of the gap in the wafer.
[0036] The acquisition unit is configured to acquire an image of the target area to obtain a target image of the target area.
[0037] The fitting unit is configured to perform curve fitting on a set of gap edge points in the target image by using a least square method to obtain a quadratic fitting curve, the set of gap edge points including a plurality of edge points located on a gap edge.
[0038] The second determining unit is configured to determine an offset of a vertex position of the vertex on the target image from a preset position of the gap in the target image based on the vertex position and the preset position, the vertex position being an actual position of the gap in the target image, and the preset position being a preset position of the gap when the preset orientation is reached.
[0039] The third determining unit is configured to determine an offset angle of the gap from the preset orientation based on the offset and a radius of the wafer, and to align the gap according to the offset angle so that the orientation of the gap conforms to the preset orientation.
[0040] In another aspect, an embodiment of the present application provides a computer device, which includes a processor and a memory:
[0041] The memory is configured to store program code and transmit the program code to the processor.
[0042] The processor is configured to execute the method according to the instructions in the program code.
[0043] In another aspect, an embodiment of the present application provides a computer readable storage medium, which is configured to store a computer program, the computer program being configured to execute the method according to the above aspects.
[0044] The embodiment of the present application provides a wafer alignment method and a related device, determines a target area where a notch is located in a wafer based on a center position of the wafer and a preset orientation of the notch, performs image acquisition on the target area, and obtains a target image of the target area, so that the image acquisition cost is reduced, and the image acquisition efficiency is improved. Then, the least square method is used for curve fitting on a notch edge point set in the target image, so as to obtain a quadratic fitting curve, the quadratic fitting curve can represent the contour line shape of the notch, and the subsequent determination of the orientation of the notch is facilitated, and the notch edge point set includes a plurality of edge points located on the edge of the notch. Then, based on a vertex position of the vertex on the quadratic fitting curve in the target image and a preset position of the notch in the target image, an offset amount of the vertex position from the preset position is determined, the vertex position is an actual position of the notch in the target image, and the preset position is a preset position of the notch when reaching the preset orientation; based on the offset amount and the radius of the wafer, an offset angle of the notch from the preset orientation is determined, and the notch is aligned according to the offset angle, so that the orientation of the notch conforms to the preset orientation. In this way, the offset amount can accurately reflect how much the actual position of the notch deviates from the preset position, and since the depth of the notch is negligible compared with the radius of the wafer, the offset amount can be approximated as the offset arc length of the notch, and then according to the relationship between the arc length and the radius of the wafer, the offset angle of the notch can be accurately calculated, and the wafer is quickly and accurately aligned through the notch. BRIEF DESCRIPTION OF DRAWINGS
[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.
[0046] Figure 1 A flowchart of a wafer alignment method provided by the embodiment of the present application is shown;
[0047] Figure 2 A top view of a wafer provided by the embodiment of the present application is shown;
[0048] Figure 3 A schematic diagram of a target image provided by the embodiment of the present application is shown;
[0049] Figure 4 A structural block diagram of a wafer alignment device provided by the embodiment of the present application is shown;
[0050] Figure 5 A structural diagram of a computer device provided by the embodiment of the present application is shown. DETAILED DESCRIPTION
[0051] In order to make the above objectives, characteristics and advantages of the present application more apparent, more comprehensible, the specific embodiments of the present application are described in detail below with reference to the drawings.
[0052] In the following description, a lot of specific details are set forth in order to facilitate a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.
[0053] Secondly, the present application is described in detail in combination with the schematic diagram, in the detailed description of the embodiments of the present application, for the convenience of description, the sectional view of the device structure will be partially enlarged without the general proportion, and the schematic diagram is only an example, which should not limit the scope of protection of the present application here. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in actual manufacture.
[0054] As described in the background, how to quickly and accurately identify the angle of the notch to accurately align the notch has become a technical problem that needs to be solved at present. In the related art, there are usually the following ways to position the wafer notch. Way one, whole scanning method, image acquisition and analysis are performed on the whole edge of the wafer to calculate the Notch position, this method needs to scan a large range of images, the calculation amount is large, the processing time is long, and the real-time performance is poor. Way two, template matching method, template matching is used in the image to identify Notch features. This method is prone to failure under the condition of light change or Notch edge defect, and the robustness is insufficient. Way three, simple edge detection method, only the Notch position is directly judged through the edge point, but the curve fitting process is lacked, the positioning accuracy is limited by noise and image resolution, it is difficult to meet the sub-micron level alignment requirement. The above ways take a long time to calculate, cannot meet the demand of high-speed production line, are not robust enough to image noise and notch deformation, are prone to cause positioning error, and cannot realize the extraction of Notch vertex with sub-pixel accuracy, the positioning accuracy is insufficient.
[0055] To solve the above technical problems, the embodiments of the present application provide a wafer alignment method and related device, which determines a target region in which a notch is located in a wafer based on a center position of the wafer and a preset orientation of the notch in the wafer, performs image acquisition on the target region to obtain a target image of the target region, thereby reducing the image acquisition cost and improving the image acquisition efficiency. Then, the embodiments of the present application perform curve fitting on a notch edge point set in the target image by using a least square method to obtain a quadratic fitting curve, the quadratic fitting curve can represent the contour line shape of the notch, which is convenient for subsequent determination of the orientation of the notch, and the notch edge point set includes a plurality of edge points located on the edge of the notch. Then, the embodiments of the present application determine an offset amount by which a vertex position deviates from a preset position based on the vertex position on the quadratic fitting curve in the target image and the preset position of the notch in the target image, the vertex position is an actual position of the notch in the target image, and the preset position is a preset position of the notch when reaching the preset orientation; determine a deviation angle by which the notch deviates from the preset orientation based on the offset amount and a radius of the wafer, and align the notch according to the deviation angle, so that the orientation of the notch conforms to the preset orientation. In this way, the offset amount can accurately reflect how much the actual position of the notch deviates from the preset position, and since the depth of the notch can be ignored relative to the radius of the wafer, the offset amount can be approximated as the arc length by which the notch deviates from the corresponding arc, and then according to the relationship between the arc length and the radius of the wafer, the deviation angle of the notch can be accurately calculated, thereby realizing fast and accurate notch alignment.
[0056] The wafer alignment method provided by the embodiments of the present application can be implemented by a computer device, which can be a terminal device or a server. The server can be a standalone physical server, a server cluster composed of multiple physical servers, or a distributed system, or a cloud server providing cloud computing services. The terminal device includes but is not limited to a mobile phone, a computer, a smart voice interaction device, a smart home appliance, a vehicle-mounted terminal, etc. The terminal device and the server can be connected directly or indirectly through wired or wireless communication, and the present application does not make any limitation in this regard.
[0057] For the convenience of understanding, the wafer alignment method and related device provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.
[0058] Reference Figure 1 As shown in the figure, the flowchart of the wafer alignment method provided by the embodiments of the present application can include the following steps.
[0059] S101, determine a target region in which a notch is located in a wafer based on a center position of the wafer and a preset orientation of the notch in the wafer.
[0060] Specifically, the center position of the wafer and a preset orientation of the notch in the wafer can be obtained through an aligner, the preset orientation can reflect a general range of the notch angle, the notch angle is an angle between a line where the notch and the center of the wafer are located and a reference line, for example, a line vertically downward. According to the center position of the wafer and the preset orientation of the notch, it can be determined that the notch is in which part of the wafer, that is, a target region where the notch is located. As an example, the target region is a lower region of the wafer surface.
[0061] As an example, referring to FIG. 1, Figure 2 a wafer 101 is shown, the wafer 101 has a U-shaped notch 1011 directly below, the wafer 101 is photographed at three photographing positions, so that the center position of the wafer 101 (that is, a preset wafer center) can be determined, Figure 2 the U-shaped notch 1011 is not aligned directly below, and needs to be aligned and adjusted subsequently.
[0062] S102, image acquisition is performed on the target region to obtain a target image of the target region.
[0063] Specifically, the target region is used to limit the image acquisition range, so as to realize local image acquisition on the region where the notch is located, thereby obtaining the target image corresponding to the target region. The main body of the target image is the notch, that is, the target image is an image of the notch.
[0064] S103, curve fitting is performed on a notch edge point set in the target image through a least square method to obtain a quadratic fitting curve, the notch edge point set includes a plurality of edge points located on the edge of the notch;
[0065] Specifically, the notch edge point set can be reflected in the target image, the notch edge point set refers to a set of points located on the edge of the notch, that is, the plurality of edge points located on the edge of the notch. The notch edge point set can be fitted through the least square method, thereby obtaining the quadratic fitting curve. The quadratic fitting curve can represent the appearance and orientation of the notch, which can be used to determine the accurate angle of the notch subsequently.
[0066] In actual application, since the notch is generally V-shaped or U-shaped, the quadratic fitting curve is:
[0067] ;
[0068] or, ;
[0069] Specifically, which formula is used depends on the orientation of the notch in the target image. If the orientation is upward or downward, the quadratic fitting curve is , if the orientation is leftward or rightward, the quadratic fitting curve is .
[0070] Wherein, about upward, downward, leftward and rightward, in the present application, the gap angle is not strictly limited to 0°, 90°, etc., for example, about downward, it can be considered that the corresponding gap angle range is within -45° to 45°, and the gap angle is not strictly limited to 0°.
[0071] In a possible implementation, before the step S103 of performing curve fitting on the gap edge point set in the target image by the least square method to obtain the quadratic fitting curve, the method can further include: performing edge detection on the target image to obtain an initial edge point set in the target image, the initial edge point set including a plurality of edge points located on the gap edge and edge points located on other regions of the wafer except the gap; and the step S103 of performing curve fitting on the gap edge point set in the target image by the least square method to obtain the quadratic fitting curve includes: performing curve fitting on the initial edge point set in the target image by the least square method to obtain the quadratic fitting curve.
[0072] Specifically, edge detection can be performed on the target region, and the edge detection can be implemented by using a Canny operator or a Sobel operator, etc., so as to obtain an initial edge point set in the target image. In the initial edge point set, a plurality of edge points located on the gap edge and edge points located on the wafer except the gap, such as points on the wafer arc edge and points located on the edges of each chip in the wafer, etc. are included. In order to improve the efficiency of wafer alignment, curve fitting can be directly performed on the initial edge point set to obtain the quadratic fitting curve.
[0073] In a possible implementation, the curve fitting on the initial edge point set in the target image by the least square method to obtain the quadratic fitting curve includes: if the quadratic fitting curve does not meet the curve requirement, performing region of interest (ROI) screening processing on the initial edge point set to obtain a gap edge point set; and performing curve fitting on the gap edge point set in the target image by the least square method to obtain the quadratic fitting curve.
[0074] In order to further reduce the data processing amount and ensure that the quadratic fitting curve can accurately represent the morphology of the gap, if the quadratic fitting curve obtained by the initial fitting does not meet the curve requirement, for example, the edge points of the wafer chip (i.e. the edge points of the wafer except the gap) are also involved in the fitting, resulting in that the quadratic fitting curve is too large and not accurate enough, at this time, the initial edge point set can be screened by a region of interest (ROI) to screen out the edge points located on the gap edge to form a gap edge point set, and to eliminate invalid background points, such as the edge points on each chip of the wafer, and then the gap edge point set is re-fitted, so as to avoid the influence of other irrelevant points on the accuracy of subsequent curve fitting, thereby greatly improving the accuracy of the gap angle determination and the gap alignment accuracy.
[0075] In a possible implementation, before performing edge detection on the target image to obtain an initial set of edge points in the target image, the method can further include: performing grayscale normalization processing, filtering and noise reduction processing, and edge enhancement processing on the target image.
[0076] Specifically, before performing the screening of the edge points, the target image can be preprocessed, such as performing grayscale normalization processing, filtering and noise reduction processing, and edge enhancement processing. Thus, the grayscale ranges of a large number of target images are kept consistent, such as being within the range of 0-255, and the noise points in the target image are removed, thereby further improving the clarity and accuracy of the target image and further reducing the adverse effects of irrelevant points on the edge points of the gap.
[0077] In a possible implementation, in the curve fitting process, the edge points in the set of edge points of the gap are subjected to outlier removal processing by using a random sample consensus algorithm (RANSAC), to obtain a quadratic fitting curve that meets a preset accuracy requirement. Thus, only the accurate edge points are used for quadratic curve fitting, and the robustness of the fitting is improved.
[0078] S104, based on a vertex position of the vertex on the quadratic fitting curve in the target image and a preset position of the gap in the target image, determining an offset amount of the vertex position from the preset position, the vertex position being an actual position of the gap in the target image, and the preset position being a preset position of the gap when the gap reaches a preset orientation.
[0079] Specifically, the gap has a preset position in the target image, and the preset position refers to the position of the gap when the gap is in a desired preset orientation. As an example, when the preset orientation is a direction upward in the plane of the wafer, due to errors in process operation, the actual orientation of the wafer is not exactly upward, but can be 1° different from the vertical upward direction. In this case, the preset orientation is the vertical upward direction, and the preset position is the position of the gap that is vertically upward. The position of the gap can be the position of the innermost point of the V-shaped or U-shaped gap, i.e., the position of the vertex of the gap.
[0080] Since the preset position can represent the position of the gap when the gap meets the preset orientation, and in combination with the actual position of the gap at this time, i.e., the vertex position of the vertex on the quadratic fitting curve in the target image, the deviation amount between the actual position of the vertex of the gap and the ideal preset position can be obtained. The deviation amount is, for example, the coordinate difference between the actual position and the preset position, i.e., the distance difference between the actual position and the preset position in the horizontal and vertical directions.
[0081] In a possible implementation, the S104 determines the offset of the vertex position from the preset position based on the vertex position on the quadratic fitting curve in the target image and the preset position of the notch in the target image, which can include S1041-S1042.
[0082] S1041, determines the image center position of the target image, and the image center position is the preset position of the notch when reaching the preset orientation.
[0083] Specifically, the image center position is the position at the center of the target image, and when the notch reaches the preset orientation, the preset position of the notch in the target image is the image center position, that is, the image center position can represent the position of the notch vertex in the target image when the orientation of the notch meets the demand.
[0084] As an example, referring to Figure 3 , a schematic diagram of a target image provided by an embodiment of the present application is shown, the block represents the area of the target image 102 collected on the wafer 101, the dashed line represents the V-shaped notch 1011 reaching the preset orientation (vertically upward), and the vertex of the dashed line is the preset position of the notch 1011 when reaching the preset orientation. The preset position is exactly located at the center point of the target image 102, and the solid line represents the misaligned V-shaped notch 1011, and the vertex of the solid line is located at the actual position, that is, the vertex position in the target image 102.
[0085] S1042, determines the offset of the vertex position from the image center position based on the vertex position on the quadratic fitting curve in the target image and the image center position.
[0086] Specifically, since the vertex position on the quadratic fitting curve in the target image represents the vertex position of the misaligned notch, and the image center position represents the vertex position of the aligned notch, the offset between the vertex position of the misaligned notch and the vertex position of the aligned notch can be determined based on the two vertex positions. The offset can be an offset in the horizontal direction, an offset in the vertical direction, or an overall offset in the plane of the wafer.
[0087] In this way, by using the image center position as a measurement reference for whether the wafer notch is aligned, since the coordinates of the image center position can be more easily obtained, the offset can be more easily calculated, and the deviation of the wafer notch from the preset orientation can be more quickly and accurately determined.
[0088] In a possible implementation, when the orientation of the gap in the target image is downward or upward, S1041, determining the image center position of the target image can include: determining the horizontal coordinate of the image center of the target image based on the horizontal size of the target image; and S1042, determining the offset of the vertex position from the image center position based on the vertex position of the vertex on the quadratic fitting curve in the target image and the image center position can include: determining the offset of the vertex position from the image center position based on the vertex horizontal coordinate of the vertex on the quadratic fitting curve in the target image and the horizontal coordinate of the image center.
[0089] Specifically, when the orientation of the gap in the target image is downward or upward, it indicates that the opening of the quadratic fitting curve is also downward or upward, at this time, the offset of the gap in the horizontal direction will be much larger than the offset in the vertical direction, as shown in Figure 3 .
[0090] Based on this, the horizontal coordinate of the image center point in the target image can be determined according to the horizontal size of the target image, and then the difference between the two horizontal coordinates can be calculated according to the vertex horizontal coordinate of the vertex of the quadratic fitting curve, so as to determine the offset of the actual position of the gap from the preset position in the horizontal direction.
[0091] In actual application, the vertex coordinate of the quadratic fitting curve may be represented as:
[0092] , ;
[0093] The offset may be represented by the following formula: wherein, is the vertex horizontal coordinate of the vertex on the quadratic fitting curve in the target image, is the horizontal size of the target image, is the horizontal coordinate of the image center. In this way, the calculation amount in the offset calculation process can be reduced, and a sufficiently accurate offset can be obtained more quickly.
[0094] In a possible implementation, when the orientation of the gap in the target image is left or right, S1041, determining the image center position of the target image can include: determining the vertical coordinate of the image center of the target image based on the vertical size of the target image; and S1042, determining the offset of the vertex position from the image center position based on the vertex position of the vertex on the quadratic fitting curve in the target image and the image center position can include: determining the offset of the vertex position from the image center position based on the vertex vertical coordinate of the vertex on the quadratic fitting curve in the target image and the vertical coordinate of the image center.
[0095] Specifically, when the orientation of the gap in the target image is left or right, it indicates that the opening of the quadratic fitting curve is also left or right, at this time, the offset of the gap in the longitudinal direction will be much larger than that in the transverse direction. Based on this, the longitudinal coordinate of the image center point in the target image can be determined according to the longitudinal size of the target image, and then the difference between the two longitudinal coordinates can be calculated according to the vertex longitudinal coordinate of the vertex of the quadratic fitting curve, so as to determine the offset of the actual position of the gap from the preset position in the longitudinal direction.
[0096] In actual application, the offset may be represented by the following formula: wherein, is the vertex longitudinal coordinate of the vertex on the quadratic fitting curve in the target image, is the longitudinal size of the target image, is the longitudinal coordinate of the image center, so as to reduce the calculation amount in the offset calculation process and obtain a sufficient accurate offset faster.
[0097] S105, based on the offset and the radius of the wafer, determines the deviation angle of the gap from the preset orientation, and aligns the gap according to the deviation angle, so that the orientation of the gap conforms to the preset orientation.
[0098] That is, the offset can reflect the transverse size of the wafer gap deviating from the preset orientation, and the deviation angle of the gap from the preset orientation can be calculated by combining the radius of the wafer, and the obtained deviation angle is output to the host computer or the process control module, so as to realize the gap alignment according to the deviation angle, so that the orientation of the gap conforms to the preset orientation.
[0099] In this way, the offset can accurately reflect how much the actual position of the gap deviates from the preset position, and since the depth of the gap is negligible relative to the radius of the wafer, the offset can be approximated as the arc length of the gap deviating from the corresponding arc length, and then according to the relationship between the arc length and the radius of the wafer, the deviation angle of the gap can be accurately calculated, and the wafer can be quickly and accurately aligned through the gap.
[0100] In one possible implementation, S105, when the proportion of the depth of the gap relative to the radius of the wafer is less than a preset proportion, based on the offset and the radius of the wafer, determines the deviation angle of the gap from the preset orientation, which can include: determining the offset as the arc length between the gap and the preset orientation; based on the ratio of the arc length and the radius of the wafer, determining the deviation angle of the gap from the preset orientation.
[0101] Specifically, if the depth of the gap , the notch depth is too small relative to the wafer radius R=150mm (12-inch wafer), i.e. the ratio of the notch depth to the wafer radius is too small and lower than the preset ratio, at this time, the notch vertex can be considered to approximately fall on the wafer circumference, and the offset is approximately equal to the arc length s: .
[0102] According to the relationship between the arc length and the radius, the deviation angle of the notch from the preset orientation can be calculated :
[0103] .
[0104] In this way, when the wafer notch size is small, the deviation angle can be quickly determined through approximate calculation, and the deviation angle meets the accuracy requirement.
[0105] In addition, the present application greatly reduces the calculation amount and improves the notch alignment speed since the entire area of the wafer does not need to be scanned; through quadratic curve fitting and sub-pixel extraction, the positioning accuracy reaches the sub-micron level; the calculation accuracy of the deviation angle can reach 0.01°, the sub-pixel refers to the specific position of the edge point falling on a single pixel, and the accuracy of the edge point is improved. Moreover, the present method has strong fault tolerance to edge noise and defects, can adapt to notch images under different process conditions, and has stronger robustness. In addition, the present method is easy to integrate, the algorithm is simple, the calculation efficiency is high, and can be directly embedded into a wafer alignment device to realize online detection.
[0106] Based on the wafer alignment method, the present application further provides a wafer alignment device, as shown in Figure 4 , a structural block diagram of a wafer alignment device provided by the present application, which can include:
[0107] The first determination unit 201 is configured to determine a target area in which the notch is located in the wafer based on the center position of the wafer and the preset orientation of the notch in the wafer.
[0108] The acquisition unit 202 is configured to acquire an image of the target area to obtain a target image of the target area.
[0109] The fitting unit 203 is configured to perform curve fitting on a notch edge point set in the target image by using the least square method to obtain a quadratic fitting curve, the notch edge point set including a plurality of edge points located on the notch edge.
[0110] The second determining unit 204 is configured to determine an offset of the vertex position from the preset position based on the vertex position of the vertex on the quadratic fitting curve in the target image and the preset position of the notch in the target image, the vertex position being an actual position of the notch in the target image, and the preset position being a preset position of the notch when reaching the preset orientation.
[0111] The third determining unit 205 is configured to determine an offset angle of the notch from the preset orientation based on the offset and a radius of the wafer, and align the notch according to the offset angle so that the orientation of the notch conforms to the preset orientation.
[0112] Optionally, the second determining unit is configured to:
[0113] determine a center position of the target image, the center position being the preset position of the notch when reaching the preset orientation.
[0114] determine the offset of the vertex position from the center position of the target image based on the vertex position of the vertex on the quadratic fitting curve in the target image and the center position.
[0115] Optionally, when the orientation of the notch in the target image is downward or upward, the second determining unit is configured to:
[0116] determine a horizontal coordinate of the center of the target image based on a horizontal size of the target image.
[0117] The determination of the offset of the vertex position from the center position of the target image based on the vertex position of the vertex on the quadratic fitting curve in the target image and the center position includes:
[0118] determination of the offset of the vertex position from the center position of the target image based on a horizontal coordinate of the vertex on the quadratic fitting curve in the target image and a horizontal coordinate of the center.
[0119] Optionally, when the orientation of the notch in the target image is left or right, the second determining unit is configured to:
[0120] determine a vertical coordinate of the center of the target image based on a vertical size of the target image.
[0121] The determination of the offset of the vertex position from the center position of the target image based on the vertex position of the vertex on the quadratic fitting curve in the target image and the center position includes:
[0122] determine an offset of the vertex position from the image center position based on a vertical coordinate of the vertex on the quadratic fitting curve in the target image and a vertical coordinate of the image center.
[0123] Optionally, the apparatus further comprises:
[0124] a detection unit, configured to perform edge detection on the target image to obtain an initial edge point set in the target image, the initial edge point set comprising a plurality of edge points on the notch edge and edge points on other regions of the wafer except the notch;
[0125] the fitting unit is configured to:
[0126] perform curve fitting on the initial edge point set in the target image by the least square method to obtain the quadratic fitting curve.
[0127] Optionally, the fitting unit is configured to:
[0128] if the quadratic fitting curve does not meet the curve requirement, perform region of interest screening processing on the initial edge point set to obtain the notch edge point set;
[0129] perform curve fitting on the notch edge point set in the target image by the least square method to obtain the quadratic fitting curve.
[0130] Optionally, the apparatus further comprises:
[0131] a processing unit, configured to perform gray scale normalization processing, filtering and noise reduction processing and edge enhancement processing on the target image.
[0132] Optionally, in the curve fitting process, the edge points in the notch edge point set are subjected to outlier removal processing by a random sample consensus algorithm to obtain the quadratic fitting curve meeting a preset accuracy requirement.
[0133] Optionally, the third determination unit is configured to:
[0134] determine the offset as an arc length between the notch and the preset orientation.
[0135] determine an offset angle of the notch from the preset orientation based on a ratio of the arc length to a radius of the wafer.
[0136] In yet another aspect, an embodiment of the present application provides a computer device, as shown in Figure 5 FIG. 1 is a structural diagram of a computer device provided by an embodiment of the present application, which comprises a processor 310 and a memory 320.
[0137] The memory 320 is configured to store a program code and transmit the program code to the processor 310.
[0138] The processor 310 is configured to execute the method provided by the above-described embodiments according to instructions in the program code.
[0139] The computer device can include a terminal device or a server, and the foregoing apparatus can be configured in the computer device.
[0140] In another aspect, the embodiments of the present application further provide a storage medium, configured to store a computer program, and the computer program is configured to execute the method provided by the above-described embodiments.
[0141] Those skilled in the art can understand that all or part of the steps of the above-mentioned method embodiments can be completed by a program instruction hardware, and the foregoing program can be stored in a computer readable storage medium, and the program is executed to execute the steps of the above-mentioned method embodiments; and the foregoing storage medium can be at least one of the following mediums: read-only memory (English: Read-only Memory, abbreviation: ROM), RAM, magnetic disk or optical disk and various mediums capable of storing program codes.
[0142] The terms "first", "second", "third", "fourth" and the like in the description of this application and the above-described drawings (if any) are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.
[0143] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other, and each embodiment focuses on the difference from other embodiments. Especially, for the device embodiments, since they are basically similar to the method embodiments, they are described more simply, and the relevant parts can be referred to the part of the method embodiments.
[0144] The above description is only the preferred embodiment of the present application, although the present application has been disclosed as above with the preferred embodiment, however, not to limit the present application. Any skilled person in the art, without departing from the scope of the technical scheme of the present application, can utilize the above disclosed methods and technical contents to make many possible changes and modifications to the technical scheme of the present application, or modify as equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the content of the technical scheme of the present application, still belongs to the scope of protection of the technical scheme of the present application.
Claims
1. A wafer alignment method, characterized in that, include: Based on the center position of the wafer and the preset orientation of the notch in the wafer, the target area where the notch is located in the wafer is determined; Image acquisition is performed on the target area to obtain a target image of the target area; The set of edge points of the gap in the target image is fitted with a curve by least squares method to obtain a quadratic fitting curve. The set of edge points of the gap includes multiple edge points located on the edge of the gap. Based on the vertex position of the vertex on the quadratic fitting curve in the target image and the preset position of the gap in the target image, the offset of the vertex position from the preset position is determined. The vertex position is the actual position of the gap in the target image, and the preset position is the preset position of the gap when it reaches the preset orientation. Based on the offset and the radius of the wafer, the deviation angle of the notch from the preset orientation is determined, and the notch is aligned according to the deviation angle so that the orientation of the notch conforms to the preset orientation.
2. The method according to claim 1, characterized in that, The step of determining the offset of the vertex position from the preset position based on the vertex position of the quadratic fitting curve in the target image and the preset position of the gap in the target image includes: Determine the image center position of the target image, where the image center position is the preset position where the notch is located when it reaches the preset orientation; Based on the vertex position of the vertex on the quadratic fitting curve in the target image and the image center position, the offset of the vertex position from the image center position is determined.
3. The method according to claim 2, characterized in that, When the notch is oriented downwards or upwards in the target image, determining the image center position of the target image includes: Based on the horizontal dimension of the target image, determine the horizontal coordinate of the image center of the target image; The step of determining the offset of the vertex position from the image center position based on the vertex position of the quadratic fitting curve in the target image and the image center position includes: Based on the x-coordinate of the vertex on the quadratic fitting curve in the target image and the x-coordinate of the image center, the offset of the vertex position from the image center position is determined.
4. The method according to claim 2, characterized in that, When the notch is oriented to the left or right in the target image, determining the image center position of the target image includes: Based on the vertical dimension of the target image, determine the vertical coordinate of the image center of the target image; The step of determining the offset of the vertex position from the image center position based on the vertex position of the quadratic fitting curve in the target image and the image center position includes: Based on the ordinate of the vertex on the quadratic fitting curve in the target image and the ordinate of the image center, the offset of the vertex position from the image center position is determined.
5. The method according to claim 1, characterized in that, Before performing curve fitting on the set of gap edge points in the target image using the least squares method to obtain a quadratic fitting curve, the method further includes: Edge detection is performed on the target image to obtain an initial set of edge points in the target image. The initial set of edge points includes multiple edge points located on the edge of the notch, as well as edge points located in other regions of the wafer other than the notch. The step of performing curve fitting on the set of gap edge points in the target image using the least squares method to obtain a quadratic fitting curve includes: The initial edge point set in the target image is fitted with a curve using the least squares method to obtain the quadratic fitting curve.
6. The method according to claim 5, characterized in that, The step of performing curve fitting on the initial edge point set in the target image using the least squares method to obtain the quadratic fitting curve includes: If the quadratic fitting curve does not meet the curve requirements, the initial edge point set is subjected to region of interest filtering to obtain the gap edge point set; The least squares method is used to fit the set of gap edge points in the target image to obtain the quadratic fitting curve.
7. The method according to claim 5, characterized in that, Before performing edge detection on the target image to obtain an initial set of edge points in the target image, the method further includes: The target image is subjected to grayscale normalization, filtering and noise reduction, and edge enhancement.
8. The method according to claim 1, characterized in that, During the curve fitting process, anomaly removal processing is performed on the edge points in the gap edge point set using a random sampling consensus algorithm to obtain the quadratic fitting curve that meets the preset accuracy requirements.
9. The method according to claim 1, characterized in that, When the ratio of the notch depth to the radius of the wafer is less than a preset ratio, determining the deviation angle of the notch from the preset orientation based on the offset and the radius of the wafer includes: The offset is determined as the arc length between the notch and the preset orientation; Based on the ratio of the arc length to the radius of the wafer, the deviation angle of the notch from the preset orientation is determined.
10. A wafer alignment apparatus, characterized in that, include: The first determining unit is used to determine the target area of the notch in the wafer based on the center position of the wafer and the preset orientation of the notch in the wafer; The acquisition unit is used to acquire images of the target area to obtain a target image of the target area; The fitting unit is used to perform curve fitting on the set of edge points of the gap in the target image using the least squares method to obtain a quadratic fitting curve. The set of edge points of the gap includes multiple edge points located on the edge of the gap. The second determining unit is used to determine the offset of the vertex position from the preset position based on the vertex position of the vertex on the quadratic fitting curve in the target image and the preset position of the gap in the target image. The vertex position is the actual position of the gap in the target image, and the preset position is the preset position of the gap when it reaches the preset orientation. The third determining unit is used to determine the deviation angle of the notch from the preset orientation based on the offset and the radius of the wafer, and to align the notch according to the deviation angle so that the orientation of the notch conforms to the preset orientation.
11. A computer device, characterized in that, The computer device includes a processor and memory: The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute the method described in any one of claims 1-9 according to the instructions in the program code.
12. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store a computer program for performing the method according to any one of claims 1-9.