Wafer scanning method, device, apparatus and storage medium

Abstract

This invention discloses a wafer scanning method, apparatus, device, and storage medium, belonging to the field of wafer scanning technology. The invention determines the scanning starting point of the wafer and performs automatic focusing based on this starting point to generate a bi-peak curve. During wafer scanning, focusing control is performed according to the bi-peak curve. After focusing is completed, the movement position of the motion platform is detected; the wafer scanning sharpness is calculated; and trajectory planning is performed based on the sharpness to complete the wafer scanning. This invention solves the problems of existing image focusing methods being unable to quickly determine the defocus direction and the difficulty in quickly and stably determining boundaries and planning paths during wafer scanning, thus improving the efficiency and effectiveness of wafer scanning.

Description

Technical Field

[0001] This invention relates to the field of wafer scanning technology, and more particularly to a wafer scanning method, apparatus, device, and storage medium. Background Technology

[0002] Wafer surface scanning inspection systems acquire quality information about the wafer surface by moving and photographing it. Because the wafer surface unit modules are tiny, optical microscopy systems are typically used for wafer surface image acquisition. However, the depth of field for clear imaging with these microscopic optical systems is very small. When there are assembly deviations in the scanning system or warping of the wafer surface, automatic focusing of the wafer surface is necessary during moving and photographing to ensure the clarity of the acquired image.

[0003] Current focusing solutions commonly employ ranging and image processing methods. Ranging corrects for deflection distance using independent measuring equipment, but its implementation and installation are complex and costly. Furthermore, ranging cannot handle wafer boundary identification, necessitating the introduction of additional equipment or algorithms for boundary trajectory planning, resulting in equipment redundancy. Existing image processing methods, relying on a single image, cannot determine the defocus direction and often require multiple acquisitions at different defocus levels, severely hindering the improvement of detection speed. Summary of the Invention

[0004] The main objective of this invention is to provide a wafer scanning method, apparatus, device, and storage medium, aiming to solve the technical problem of low wafer scanning efficiency in the prior art.

[0005] To achieve the above objectives, the present invention provides a wafer scanning method, the method comprising the following steps:

[0006] The scanning start point of the wafer is determined, and autofocus is performed based on the scanning start point to generate a dual-peak curve;

[0007] During wafer scanning, focusing control is performed based on the aforementioned dual-peak curve;

[0008] After focusing is complete, the motion position of the motion platform is detected;

[0009] Calculate the sharpness of the wafer scan;

[0010] Trajectory planning is performed using the aforementioned clarity to complete wafer scanning.

[0011] Optionally, the focus control based on the bimodal curve during wafer scanning includes:

[0012] During wafer scanning, obtain the current scan position;

[0013] Calculate the defocus compensation value and determine the defocus direction based on the bipeak curve and the current scanning position;

[0014] Focusing control is performed based on the defocus compensation value and the defocus direction.

[0015] Optionally, calculating the defocus compensation value and defocus direction based on the bimodal curve and the current scanning position includes:

[0016] Based on the current scanning position and the bimodal curve, a first sharpness value and a second sharpness value are calculated using a first sharpness function and a second sharpness function, respectively.

[0017] When the first sharpness value is less than the preset defocus threshold, it is determined that defocus exists;

[0018] The first sharpness value and the second sharpness value are compared to obtain a comparison result;

[0019] Determine the defocusing direction based on the comparison results;

[0020] By fitting the bimodal curve, a first correspondence between the defocus compensation value and the first sharpness value is obtained;

[0021] Calculate the defocus compensation value based on the first correspondence and the first sharpness value.

[0022] Optionally, the step of trajectory planning based on the resolution to complete wafer scanning includes:

[0023] The resolution is compared with a preset resolution threshold;

[0024] When the resolution is less than the preset resolution threshold, the scanning device is determined to have moved to the edge position, and the wafer scanning is stopped.

[0025] Edge extraction is performed on the wafer, and displacement compensation is performed in the opposite direction;

[0026] Use the compensated position as the starting point for the update scan;

[0027] Wafer scanning is performed using the updated scan starting point.

[0028] Optionally, the step of edge extraction of the wafer and compensation for displacement in the opposite direction includes:

[0029] Edge extraction is performed on the wafer to obtain the position of wafer pixels in the field of view;

[0030] The edge wafer pixel coordinates are obtained based on the wafer pixel positions;

[0031] Obtain the second correspondence between physical size and pixel size during scanning;

[0032] The target compensation amount between the edge wafer pixel coordinates and the field of view boundary is obtained through the second correspondence;

[0033] The scanning device is controlled to move in the opposite direction according to the target compensation amount, so that the edge of the wafer coincides with the field boundary, thus completing the compensation.

[0034] Optionally, the wafer scanning via the updated scan starting point includes:

[0035] At the starting point of the update scan, when the scanning device is out of focus, the current sharpness is calculated;

[0036] The amount of defocus is calculated using the current sharpness and the bi-peak curve.

[0037] Control the focusing device to move a first preset distance in the negative direction until the current moving distance is reached;

[0038] At the current distance traveled, calculate the updated sharpness;

[0039] The landing point position is determined based on the current resolution and the updated resolution;

[0040] The target focus compensation amount is calculated based on the landing point position and the defocus amount;

[0041] Focusing is performed using the target focus compensation amount, and wafer scanning is also performed.

[0042] Optionally, determining the scanning start point of the wafer and performing autofocus based on the scanning start point to generate a bimodal curve includes:

[0043] Determine the scanning start point of the wafer, and calculate a first gradient value based on the scanning start point using a first resolution function;

[0044] Control the focusing device to move a second preset distance, and use the first sharpness function to calculate a second gradient value;

[0045] The search direction is determined by the first gradient value and the second gradient value;

[0046] Obtain the movement step size of the focusing device;

[0047] The target interval is determined by searching based on the search direction and the movement step length.

[0048] The target interval is divided and the peak value is calculated to obtain the target peak position;

[0049] The target peak position is moved in a first defocus direction and a second defocus direction, and a first sample sharpness and a second sample sharpness are calculated at each position using a first sharpness function and a second sharpness function;

[0050] A bimodal curve is generated based on the sharpness of the first sample and the sharpness of the second sample.

[0051] Furthermore, to achieve the above objectives, the present invention also proposes a wafer scanning device, the wafer scanning device comprising:

[0052] The determination module is used to determine the scanning start point of the wafer and perform automatic focusing based on the scanning start point to generate a dual-peak curve;

[0053] The control module is used to perform focus control based on the dual-peak curve during wafer scanning;

[0054] The detection module is used to detect the movement position of the motion platform after focusing is completed;

[0055] The calculation module is used to calculate the sharpness of the wafer scan;

[0056] The planning module is used to plan the trajectory based on the resolution to complete the wafer scanning.

[0057] Furthermore, to achieve the above objectives, the present invention also proposes a wafer scanning device, the wafer scanning device comprising: a memory, a processor, and a wafer scanning program stored in the memory and executable on the processor, the wafer scanning program being configured to implement the steps of the wafer scanning method as described above.

[0058] In addition, to achieve the above objectives, the present invention also proposes a storage medium storing a wafer scanning program, which, when executed by a processor, implements the steps of the wafer scanning method as described above.

[0059] This invention determines the scanning start point of the wafer and performs automatic focusing based on the scanning start point to generate a bi-peak curve. During wafer scanning, focusing control is performed according to the bi-peak curve. After focusing is completed, the motion position of the motion platform is detected. The sharpness of the wafer scan is calculated. The trajectory is planned based on the sharpness to complete the wafer scan. This invention solves the problems of existing image focusing methods that cannot quickly determine the defocus direction and the difficulty in quickly and stably determining the boundary and planning the path during wafer scanning, thereby improving the efficiency and effectiveness of wafer scanning. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the structure of a wafer scanning device in the hardware operating environment involved in the embodiments of the present invention;

[0061] Figure 2 This is a schematic flowchart of the first embodiment of the wafer scanning method of the present invention;

[0062] Figure 3 This is a schematic flowchart of the second embodiment of the wafer scanning method of the present invention;

[0063] Figure 4 This is a schematic diagram illustrating the focus control during wafer scanning in one embodiment of the wafer scanning method of the present invention;

[0064] Figure 5 This is a flowchart illustrating the third embodiment of the wafer scanning method of the present invention;

[0065] Figure 6 This is a schematic diagram of the trajectory planning process for wafer scanning in one embodiment of the wafer scanning method of the present invention;

[0066] Figure 7 This is a schematic diagram of the camera field of view and wafer position in one embodiment of the wafer scanning method of the present invention;

[0067] Figure 8 This is a schematic diagram of focusing at the update scan starting point in one embodiment of the wafer scanning method of the present invention;

[0068] Figure 9 This is a structural block diagram of the first embodiment of the wafer scanning device of the present invention.

[0069] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0070] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0071] Reference Figure 1 , Figure 1 This is a schematic diagram of the wafer scanning device structure of the hardware operating environment involved in the embodiments of the present invention.

[0072] like Figure 1As shown, the wafer scanning device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. The communication bus 1002 is used to enable communication between these components. The user interface 1003 may include a display screen or an input unit such as a keyboard; optionally, the user interface 1003 may also include a standard wired interface or a wireless interface. The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a Wireless-Fidelity (Wi-Fi) interface). The memory 1005 may be high-speed random access memory (RAM) or stable non-volatile memory (NVM), such as a disk drive. The memory 1005 may also optionally be a storage device independent of the aforementioned processor 1001.

[0073] Those skilled in the art will understand that Figure 1 The structure shown does not constitute a limitation on the wafer scanning device and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0074] like Figure 1 As shown, the memory 1005, which serves as a storage medium, may include an operating system, a network communication module, a user interface module, and a wafer scanning program.

[0075] exist Figure 1 In the wafer scanning device shown, the network interface 1004 is mainly used for data communication with the network server; the user interface 1003 is mainly used for data interaction with the user; the processor 1001 and the memory 1005 in the wafer scanning device of the present invention can be set in the wafer scanning device, and the wafer scanning device calls the wafer scanning program stored in the memory 1005 through the processor 1001 and executes the wafer scanning method provided in the embodiment of the present invention.

[0076] This invention provides a wafer scanning method, referring to... Figure 2 , Figure 2 This is a schematic flowchart of the first embodiment of the wafer scanning method of the present invention.

[0077] In this embodiment, the wafer scanning method includes the following steps:

[0078] Step S10: Determine the scanning start point of the wafer and perform autofocus based on the scanning start point to generate a double peak curve.

[0079] It should be noted that the execution subject in this embodiment is a wafer scanning device, but other devices capable of performing the same or similar functions can also be used. This embodiment does not limit the scope of the embodiments; instead, it uses a wafer scanning device as an example for illustration. The wafer scanning device is mainly used for focusing and trajectory planning during wafer scanning. It primarily includes a focusing device and a scanning device.

[0080] This embodiment mainly addresses the problem of not being able to quickly achieve autofocus, boundary positioning, and trajectory planning during wafer scanning. It is mainly divided into an autofocus part and a boundary positioning path planning part. The autofocus part is mainly used for overall focus correction of the equipment before scanning begins and for automatic focusing after defocusing during scanning. The boundary positioning planning part is mainly used for trajectory planning through image processing recognition when scanning to the wafer boundary position. The two parts work together to achieve focus and path planning for the entire wafer scanning.

[0081] In practice, to improve scanning accuracy, the scanning equipment can be automatically focused before wafer scanning. This allows the starting point of the wafer scan to be determined first, and automatic focusing to be performed based on the starting point, thereby generating a double-peak curve.

[0082] It should be noted that the bimodal curve is an initial curve generated using the sharpness values ​​calculated using the first sharpness function and the second sharpness function, and a non-confocal bimodal curve is formed by normalizing the initial curve.

[0083] Optionally, step S10 specifically includes:

[0084] Determine the scanning start point of the wafer, and calculate a first gradient value based on the scanning start point using a first resolution function;

[0085] Control the focusing device to move a second preset distance, and use the first sharpness function to calculate a second gradient value;

[0086] The search direction is determined by the first gradient value and the second gradient value;

[0087] Obtain the movement step size of the focusing device;

[0088] The target interval is determined by searching based on the search direction and the movement step length.

[0089] The target interval is divided and the peak value is calculated to obtain the target peak position;

[0090] The target peak position is moved in a first defocus direction and a second defocus direction, and a first sample sharpness and a second sample sharpness are calculated at each position using a first sharpness function and a second sharpness function;

[0091] A bimodal curve is generated based on the sharpness of the first sample and the sharpness of the second sample.

[0092] It should be noted that the scanning start point of the wafer can be determined and used as the initial focus position. The image is acquired and the first sharpness function is used as the image sharpness function for calculation, thereby obtaining the first gradient value at the initial focus position.

[0093] The first sharpness function is the Laplacian function, and the first gradient value is the sum of squares of the gradients calculated according to the Laplacian function. This can be achieved by obtaining the grayscale values ​​of the pixels in the acquired image and obtaining the convolution kernel. The sum of squares of the gradients can then be calculated using the grayscale values ​​and the convolution kernel, as shown in Equation 1 below:

[0094]

[0095] In Equation 1 above, D1 is the first gradient value, L is the convolution kernel, and f(x, y) is the gray value.

[0096] It should be noted that any direction can be set as the starting direction to control the movement of the focusing device by a second preset distance. The second preset distance Δd can be set according to the requirements. The direction of the second preset distance can be left or right. After the focusing device moves the second preset distance to the moving point, the image can be acquired again, and the second gradient value can be calculated using the first sharpness function. The calculation process is as shown in Equation 1 above, and the obtained second gradient value is D2.

[0097] The search direction can be determined by the first gradient value and the second gradient value. Specifically, the first gradient value D1 and the second gradient value D2 can be compared. If D2>D1, the search direction is consistent with the direction of the second preset distance. If D2≤D1, the search direction is opposite to the direction of the second preset distance.

[0098] In practical implementation, the movement step size of the focusing device can be obtained. The movement step size △T1 of the focusing device can be set in advance. The movement step size is the large interval search step size. Generally, a large interval is set, and the total number of intervals is M1. The binary search method can be used to continuously search according to the search direction and movement step size. Each time a certain position is searched, the peak value is calculated and compared before and after until the fine position represented by the maximum interval I1 is found, and the maximum interval is taken as the target interval.

[0099] In practice, the maximum interval can be finely divided. At this time, the movement step size is set to ΔT2, which is the small interval search step size. The same binary search and peak calculation are performed until the required peak position, i.e. the target peak position, is found.

[0100] Understandably, the target peak position can be shifted to two defocus directions, namely the first defocus direction and the second defocus direction, by several identical small intervals, and the first sharpness function and the second sharpness function can be used to calculate the first sample sharpness and the second sample sharpness at each position.

[0101] The second sharpness function is the Berner sharpness function. The first sample sharpness is the sharpness value calculated by the first sharpness function, and the second sample sharpness is the sharpness value calculated by the second sharpness function.

[0102] In practice, corresponding curves can be generated based on the sharpness of the first and second samples, and the two curves can be normalized to form a non-confocal double-peak curve.

[0103] Through the above process, the automatic focusing at the starting position is completed, and the scanning device begins to move to perform wafer scanning. The initial point is quickly focused by using the size range and the dichotomy method.

[0104] Step S20: During wafer scanning, focus control is performed based on the bimodal curve.

[0105] In practice, during wafer scanning, each movement distance corresponds to one phase imaging field of view. Therefore, a sharpness value is calculated every time the scanning device moves, allowing for focus control during the scanning process based on the bi-peak curve. For example, defocus correction can be performed when the image is out of focus.

[0106] Step S30: After focusing is completed, detect the motion position of the motion platform.

[0107] In practice, after focusing is completed, the movement position of the motion platform can be detected. For example, a position sensor can be installed on the motion platform to detect the movement position.

[0108] Step S40: Calculate the sharpness of the wafer scan.

[0109] It should be noted that when the camera's field of view is at the edge of the wafer, it often extends beyond the wafer boundary by a certain distance. Therefore, the sharpness of the wafer scan can be calculated when the camera is at the edge of the wafer.

[0110] Step S50: Perform trajectory planning based on the resolution to complete wafer scanning.

[0111] In practice, when the wafer scan moves to the edge, its resolution value will be much lower than that of the normally acquired image. Therefore, the wafer scan trajectory can be planned based on the resolution value, thereby improving the scanning accuracy when the wafer scan reaches the boundary and completing the wafer scan.

[0112] This embodiment determines the scanning starting point of the wafer and performs automatic focusing based on the scanning starting point to generate a bi-peak curve. During wafer scanning, focusing control is performed according to the bi-peak curve. After focusing is completed, the motion position of the motion platform is detected. The sharpness of the wafer scan is calculated. The trajectory is planned based on the sharpness to complete the wafer scan. This solves the problems of existing image focusing being unable to quickly determine the defocus direction and the difficulty in quickly and stably determining the boundary and planning the path during wafer scanning, thus improving the efficiency and effect of wafer scanning.

[0113] refer to Figure 3 , Figure 3 This is a schematic flowchart of the second embodiment of the wafer scanning method of the present invention.

[0114] Based on the first embodiment described above, step S20 of the wafer scanning method in this embodiment includes:

[0115] Step S201: During wafer scanning, obtain the current scanning position.

[0116] It should be noted that the current scanning position can be obtained during wafer scanning.

[0117] Step S202: Calculate the defocus compensation value and determine the defocus direction based on the bimodal curve and the current scanning position.

[0118] In practice, the defocus compensation value can be calculated based on the bimodal curve and the current scanning position, and the defocus direction can be determined.

[0119] Furthermore, the steps for calculating the defocus compensation value and determining the defocus direction specifically include:

[0120] Based on the current scanning position and the bimodal curve, a first sharpness value and a second sharpness value are calculated using a first sharpness function and a second sharpness function, respectively.

[0121] When the first sharpness value is less than the preset defocus threshold, it is determined that defocus exists;

[0122] The first sharpness value and the second sharpness value are compared to obtain a comparison result;

[0123] Determine the defocusing direction based on the comparison results;

[0124] By fitting the bimodal curve, a first correspondence between the defocus compensation value and the first sharpness value is obtained;

[0125] Calculate the defocus compensation value based on the first correspondence and the first sharpness value.

[0126] Understandably, a first sharpness value is calculated using a first sharpness function based on the current scan position and the bimodal curve, and a second sharpness value is calculated using a second sharpness function.

[0127] An image can be captured at the current scanning position to obtain an acquired image, and a first sharpness value and a second sharpness value can be calculated based on the acquired image. The first sharpness value and the second sharpness value are normalized values ​​obtained by calculating the values ​​according to the first sharpness function and the second sharpness function.

[0128] In practice, the first sharpness value can be compared with a preset defocus threshold. If the first sharpness value is less than the preset defocus threshold, it is determined that the scanning device is out of focus and needs to be corrected.

[0129] In practice, the first sharpness value and the second sharpness value can be compared to determine the magnitude of the first sharpness value and the second sharpness value, and the comparison result can be obtained.

[0130] In practice, if the first sharpness value is less than the second sharpness value, the defocus direction is to the left of the defocus distance of 0. If the first sharpness value is greater than the second sharpness value, the defocus direction is to the right of the defocus distance of 0. This provides a basis for determining the defocus direction based on the acquired image.

[0131] In practical implementation, the bimodal curve can be fitted, and the fitting process is as follows: Equation 2:

[0132] y = ax m +bx m-1 +...+mx+n (Equation 2)

[0133] In Equation 2 above, y is the first sharpness value, x is the defocus compensation value, and a, b, and m are polynomial coefficients. Therefore, the first correspondence between the defocus compensation value and the first sharpness value can be obtained through Equation 2 above, and the defocus compensation value can be calculated through the first correspondence and the first sharpness value.

[0134] Step S203: Perform focus control based on the defocus compensation value and the defocus direction.

[0135] It should be noted that the defocusing of the scanning device can be corrected by adjusting the defocusing compensation value and the defocusing direction, thereby completing the correction of a single defocusing event and achieving focus control of the scanning device.

[0136] like Figure 4 As shown, Figure 4This diagram illustrates the control of focusing during wafer scanning, including initial focusing and focusing during scanning. A large-area search is performed at the initial position to calculate the peak value. A bisection method is then used for fine-grained position division and a small-area search. The peak position is calculated using the bisection method, generating the Berner and Lapalce curves, which are then normalized to generate a non-confocal double-peak curve. When defocusing begins during wafer scanning, the double peak value is used to determine the defocusing direction. A multinomial fitting method is then used to calculate the defocusing compensation value, thus compensating for defocusing based on the defocusing direction and the compensation value.

[0137] This embodiment achieves the function of simultaneous acquisition and focusing during wafer scanning by obtaining the current scanning position during wafer scanning; calculating the defocus compensation value and determining the defocus direction based on the dual-peak curve and the current scanning position; and performing focusing control according to the defocus compensation value and the defocus direction, thereby improving the wafer scanning effect.

[0138] refer to Figure 5 , Figure 5 This is a schematic flowchart of the third embodiment of the wafer scanning method of the present invention.

[0139] Based on the first embodiment described above, step S50 of the wafer scanning method in this embodiment includes:

[0140] Step S501: Compare the resolution with a preset resolution threshold.

[0141] It should be noted that the preset sharpness threshold represents the critical value at which the wafer scanning device moves to the boundary. Therefore, the sharpness can be compared with the preset sharpness threshold to determine whether the scanning device has moved to the edge position.

[0142] Step S502: When the resolution is less than the preset resolution threshold, determine that the scanning device has moved to the edge position and control the wafer scanning to stop.

[0143] Understandably, if the resolution is greater than the preset resolution threshold, it means that the scanning device has not moved to the wafer boundary, so scanning continues.

[0144] When the resolution is less than a preset resolution threshold, the scanning device can be determined to have moved to the edge position, and the wafer scanning of the scanning device can be stopped.

[0145] Step S503: Extract the edge of the wafer and compensate for the displacement in the opposite direction.

[0146] In practical implementation, edge extraction can be performed on the wafer to achieve reverse displacement compensation. For example... Figure 6 As shown, Figure 6This is a schematic diagram of the trajectory planning process for wafer scanning. By calculating the sharpness, it is determined whether it exceeds a preset sharpness threshold. If so, the scanning stops, and wafer edge extraction is performed to compensate for the displacement in the opposite direction, shifting to an adjacent movement direction for single-peak focusing. This process is repeated cyclically until the scanning continues. If the sharpness is not greater than the preset sharpness threshold, the scanning continues.

[0147] Optionally, the steps of edge extraction and reverse displacement compensation of the wafer include: edge extraction of the wafer to obtain the wafer pixel position in the field of view; obtaining the edge wafer pixel coordinates based on the wafer pixel position; obtaining a second correspondence between the physical size and the pixel size during scanning; obtaining the target compensation amount between the edge wafer pixel coordinates and the field of view boundary through the second correspondence; and controlling the scanning device to move in the reverse direction according to the target compensation amount so that the wafer edge coincides with the field of view boundary, thereby completing the compensation.

[0148] It should be noted that, as Figure 7 As shown, Figure 7 This is a schematic diagram of the camera's field of view and the wafer's position. When the camera's field of view is at the edge of the wafer, it often exceeds the wafer boundary by ΔL. Therefore, the wafer's edge can be extracted to obtain the position of the wafer pixels in the field of view. The wafer pixel coordinates of a column at the edge can be obtained by the difference in coordinate positions, i.e., the edge wafer pixel coordinates.

[0149] There is a second correspondence between the physical size of the scanning device and the pixel size. Therefore, the actual compensation amount ΔL between the pixel coordinates of the edge column and the field boundary can be obtained according to the second correspondence.

[0150] Understandably, after obtaining the target compensation amount ΔL, the scanning device can be controlled to move in the opposite direction, thereby aligning the wafer edge with the field of view boundary. For example, if the scanning device moves to the right during wafer scanning, it can be controlled to move to the left by ΔL using the target compensation amount. This direction of movement is defined as the x-direction. After the displacement compensation in the opposite direction is completed, the scanning device also shifts one field of view in the y-axis direction to obtain the compensated position.

[0151] Step S504: Use the compensated position as the starting point for the update scan.

[0152] In practice, the compensated position can be used as the starting point for updating the scan.

[0153] Step S505: Perform wafer scanning using the updated scan start point.

[0154] In practice, wafer scanning can continue by updating the scan start point.

[0155] For example, defocus compensation can also be performed during the scanning process to improve the efficiency of wafer scanning.

[0156] Furthermore, the step of performing wafer scanning through the updated scan start point includes:

[0157] At the starting point of the update scan, when the scanning device is out of focus, the current sharpness is calculated;

[0158] The amount of defocus is calculated using the current sharpness and the bi-peak curve.

[0159] Control the focusing device to move a first preset distance in the negative direction until the current moving distance is reached;

[0160] At the current distance traveled, calculate the updated sharpness;

[0161] The landing point position is determined based on the current resolution and the updated resolution;

[0162] The target focus compensation amount is calculated based on the landing point position and the defocus amount;

[0163] Focusing is performed using the target focus compensation amount, and wafer scanning is also performed.

[0164] It should be noted that at the new scanning starting point, in order to ensure that the image does not lose focus after the y-axis shift, a single-peak focusing is performed. Therefore, if the scanning device is in a defocused state at the updated scanning starting point, the current sharpness can be calculated.

[0165] When out of focus, such as Figure 8 As shown, Figure 8 This diagram illustrates focusing at the starting point of the update scan. When out of focus, the focus point may be located at point A or point B. The current sharpness can be calculated based on point A or point B. Then, the defocus amount can be calculated based on the current sharpness and the bi-peak curve. Specifically, the defocus amount is calculated as 1 / 2Δx through a curve fitting expression. By controlling the focusing device to move a first preset distance Δx in the negative direction, the current moving distance point A' or point B' can be reached.

[0166] In practice, the updated sharpness can be calculated at the current moving distance.

[0167] The location of the landing point, whether it is point A' or point B', is determined by updating the resolution and the current resolution.

[0168] Specifically, the updated resolution is compared with the current resolution. If the current resolution is approximately equal to the updated resolution, the landing point is point B'. If the current resolution is greater than the updated resolution, the landing point is point A'.

[0169] In practice, the target focus compensation amount can be calculated by the landing point position and the defocus amount. If the landing point position is point A', the target focus compensation amount is +1 / 2Δx. If the landing point position is point B', the target focus compensation amount is +(1+1 / 2Δx) = +3 / 2Δx. At this time, focusing is performed by the target focus compensation amount to complete the automatic focusing at the new starting position point and continue wafer scanning.

[0170] Through the above process, the cyclic scanning is completed, namely, automatic focusing at the starting point to generate a double-peak curve; automatic focusing based on the double-peak curve during movement; edge position identification and compensation; single-peak focusing at the starting point for a new round; automatic focusing based on the double-peak curve during continued scanning movement; edge position identification and compensation to form an S-shaped scanning trajectory, and so on until the scanning of the entire wafer is completed.

[0171] This embodiment compares the sharpness with a preset sharpness threshold; when the sharpness is less than the preset sharpness threshold, it determines that the scanning device has moved to the edge position and controls the wafer scanning to stop; it extracts the edge of the wafer and compensates for the displacement in the opposite direction; it uses the compensated position as the updated scanning starting point; it performs wafer scanning through the updated scanning starting point, and in the boundary positioning planning part, it uses the sharpness function to judge the boundary, thereby quickly planning the path for wafer scanning, solving the problem that it is difficult to quickly and stably judge the boundary and plan the path during the wafer scanning process.

[0172] Reference Figure 9 , Figure 9 This is a structural block diagram of the first embodiment of the wafer scanning device of the present invention.

[0173] like Figure 9 As shown, the wafer scanning device proposed in this embodiment of the invention includes:

[0174] The determination module 10 is used to determine the scanning start point of the wafer and perform automatic focusing based on the scanning start point to generate a double peak curve.

[0175] The control module 20 is used to perform focus control based on the dual-peak curve during wafer scanning.

[0176] The detection module 30 is used to detect the motion position of the motion platform after focusing is completed.

[0177] Calculation module 40 is used to calculate the sharpness of the wafer scan.

[0178] Planning module 50 is used to plan the trajectory based on the resolution to complete the wafer scan.

[0179] This embodiment determines the scanning starting point of the wafer and performs automatic focusing based on the scanning starting point to generate a bi-peak curve. During wafer scanning, focusing control is performed according to the bi-peak curve. After focusing is completed, the motion position of the motion platform is detected. The sharpness of the wafer scan is calculated. The trajectory is planned based on the sharpness to complete the wafer scan. This solves the problems of existing image focusing being unable to quickly determine the defocus direction and the difficulty in quickly and stably determining the boundary and planning the path during wafer scanning, thus improving the efficiency and effect of wafer scanning.

[0180] In one embodiment, the control module 20 is further configured to, during wafer scanning, acquire the current scanning position; calculate a defocus compensation value and determine the defocus direction based on the bi-peak curve and the current scanning position; and perform focusing control based on the defocus compensation value and the defocus direction.

[0181] In one embodiment, the control module 20 is further configured to calculate a first sharpness value and a second sharpness value using a first sharpness function and a second sharpness function respectively, based on the current scanning position and the bimodal curve; determine that there is defocus when the first sharpness value is less than a preset defocus threshold; compare the first sharpness value and the second sharpness value to obtain a comparison result; determine the defocus direction based on the comparison result; fit the bimodal curve to obtain a first correspondence between the defocus compensation value and the first sharpness value; and calculate the defocus compensation value based on the first correspondence and the first sharpness value.

[0182] In one embodiment, the planning module 50 is further configured to compare the sharpness with a preset sharpness threshold; when the sharpness is less than the preset sharpness threshold, determine that the scanning device has moved to the edge position and control the wafer scanning to stop; perform edge extraction on the wafer and perform reverse displacement compensation; use the compensated position as the update scanning starting point; and perform wafer scanning through the update scanning starting point.

[0183] In one embodiment, the planning module 50 is further configured to perform edge extraction on the wafer to obtain the wafer pixel position in the field of view; obtain the edge wafer pixel coordinates based on the wafer pixel position; obtain a second correspondence between the physical size and the pixel size during scanning; obtain the target compensation amount between the edge wafer pixel coordinates and the field of view boundary through the second correspondence; and control the scanning device to move in the opposite direction according to the target compensation amount so that the wafer edge coincides with the field of view boundary, thereby completing the compensation.

[0184] In one embodiment, the planning module 50 is further configured to: calculate the current sharpness at the starting point of the update scan when the scanning device is out of focus; calculate the defocus amount using the current sharpness and the bi-peak curve; control the focusing device to move a first preset distance in the negative direction to reach the current moving distance; calculate the updated sharpness at the current moving distance; determine the landing point position based on the current sharpness and the updated sharpness; calculate the target focus compensation amount using the landing point position and the defocus amount; focus using the target focus compensation amount and perform wafer scanning.

[0185] In one embodiment, the determining module 10 is further configured to: determine the scanning start point of the wafer; calculate a first gradient value based on the scanning start point using a first sharpness function; control the focusing device to move a second preset distance and calculate a second gradient value using the first sharpness function; determine a search direction using the first gradient value and the second gradient value; obtain the movement step size of the focusing device; perform a search based on the search direction and the movement step size to determine a target interval; divide the target interval and perform peak calculation to obtain a target peak position; move at the target peak position towards a first defocus direction and a second defocus direction, and calculate a first sample sharpness and a second sample sharpness at each position using the first sharpness function and the second sharpness function; and generate a bimodal curve based on the first sample sharpness and the second sample sharpness.

[0186] Furthermore, to achieve the above objectives, the present invention also proposes a wafer scanning device, the wafer scanning device comprising: a memory, a processor, and a wafer scanning program stored in the memory and executable on the processor, the wafer scanning program being configured to implement the steps of the wafer scanning method as described above.

[0187] Since this wafer scanning device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0188] Furthermore, embodiments of the present invention also propose a storage medium storing a wafer scanning program, wherein the wafer scanning program, when executed by a processor, implements the steps of the wafer scanning method described above.

[0189] Since this storage medium adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0190] It should be understood that the above are merely illustrative examples and do not constitute any limitation on the technical solutions of the present invention. In specific applications, those skilled in the art can make settings as needed, and the present invention does not impose any restrictions on this.

[0191] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of this invention. In practical applications, those skilled in the art can select some or all of the workflow to achieve the purpose of this embodiment according to actual needs, and no restrictions are imposed here.

[0192] In addition, for technical details not described in detail in this embodiment, please refer to the wafer scanning method provided in any embodiment of the present invention, which will not be repeated here.

[0193] Furthermore, it should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0194] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0195] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as read-only memory (ROM) / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0196] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A wafer scanning method, characterized in that, The wafer scanning method includes: The scanning start point of the wafer is determined, and autofocus is performed based on the scanning start point to generate a dual-peak curve; During wafer scanning, focusing control is performed based on the aforementioned dual-peak curve; After focusing is complete, the motion position of the motion platform is detected; Calculate the sharpness of the wafer scan; Trajectory planning is performed using the aforementioned clarity to complete wafer scanning; The focusing control based on the dual-peak curve during wafer scanning includes: During wafer scanning, obtain the current scan position; Calculate the defocus compensation value and determine the defocus direction based on the bipeak curve and the current scanning position; Focus control is performed based on the defocus compensation value and the defocus direction; The calculation of the defocus compensation value and defocus direction based on the bimodal curve and the current scanning position includes: Based on the current scanning position and the bimodal curve, a first sharpness value and a second sharpness value are calculated using a first sharpness function and a second sharpness function, respectively. When the first sharpness value is less than the preset defocus threshold, it is determined that defocus exists; The first sharpness value and the second sharpness value are compared to obtain a comparison result; Determine the defocusing direction based on the comparison results; By fitting the bimodal curve, a first correspondence between the defocus compensation value and the first sharpness value is obtained; Calculate the defocus compensation value based on the first correspondence and the first sharpness value; The process of determining the scanning start point of the wafer and performing automatic focusing based on the scanning start point to generate a bimodal curve includes: Determine the scanning start point of the wafer, and calculate a first gradient value based on the scanning start point using a first resolution function; Control the focusing device to move a second preset distance, and use the first sharpness function to calculate a second gradient value; The search direction is determined by the first gradient value and the second gradient value; Obtain the movement step size of the focusing device; The target interval is determined by searching based on the search direction and the movement step length. The target interval is divided and the peak value is calculated to obtain the target peak position; The target peak position is moved in a first defocus direction and a second defocus direction, and a first sample sharpness and a second sample sharpness are calculated at each position using a first sharpness function and a second sharpness function; A bimodal curve is generated based on the sharpness of the first sample and the sharpness of the second sample, wherein the bimodal curve is a non-confocal bimodal curve.

2. The wafer scanning method as described in claim 1, characterized in that, The process of trajectory planning based on the resolution to complete wafer scanning includes: The resolution is compared with a preset resolution threshold; When the resolution is less than the preset resolution threshold, the scanning device is determined to have moved to the edge position, and the wafer scanning is stopped. Edge extraction is performed on the wafer, and displacement compensation is performed in the opposite direction; Use the compensated position as the starting point for the update scan; Wafer scanning is performed using the updated scan starting point.

3. The wafer scanning method as described in claim 2, characterized in that, The process of edge extraction of the wafer and compensation for displacement in the opposite direction includes: Edge extraction is performed on the wafer to obtain the position of wafer pixels in the field of view; The edge wafer pixel coordinates are obtained based on the wafer pixel positions; Obtain the second correspondence between physical size and pixel size during scanning; The target compensation amount between the edge wafer pixel coordinates and the field of view boundary is obtained through the second correspondence; The scanning device is controlled to move in the opposite direction according to the target compensation amount, so that the edge of the wafer coincides with the field boundary, thus completing the compensation.

4. The wafer scanning method as described in claim 2, characterized in that, The wafer scanning via the updated scan starting point includes: At the starting point of the update scan, when the scanning device is out of focus, the current sharpness is calculated; The amount of defocus is calculated using the current sharpness and the bi-peak curve. Control the focusing device to move a first preset distance in the negative direction until the current moving distance is reached; At the current distance traveled, calculate the updated sharpness; The landing point position is determined based on the current resolution and the updated resolution; The target focus compensation amount is calculated based on the landing point position and the defocus amount; Focusing is performed using the target focus compensation amount, and wafer scanning is also performed.

5. A wafer scanning device, characterized in that, The wafer scanning apparatus performs the wafer scanning method according to any one of claims 1 to 4, and the wafer scanning apparatus comprises: The determination module is used to determine the scanning start point of the wafer and perform automatic focusing based on the scanning start point to generate a dual-peak curve; The control module is used to perform focus control based on the dual-peak curve during wafer scanning; The detection module is used to detect the movement position of the motion platform after focusing is completed; The calculation module is used to calculate the sharpness of the wafer scan; The planning module is used to plan the trajectory based on the resolution to complete the wafer scanning.

6. A wafer scanning device, characterized in that, The wafer scanning device includes: a memory, a processor, and a wafer scanning program stored in the memory and executable on the processor, the wafer scanning program being configured to implement the wafer scanning method as described in any one of claims 1 to 4.

7. A storage medium, characterized in that, The storage medium stores a wafer scanning program, which, when executed by a processor, implements the wafer scanning method as described in any one of claims 1 to 4.

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