Wafer detection mark positioning method and application

Abstract

The application discloses a wafer detection Mark point positioning method, comprising the following steps: acquiring all picture images under the same index of a wafer detection image, and performing coarse positioning on the corresponding picture images through a first template covering information around a to-be-detected Mark point; cutting out a coarse positioning area according to a coarse positioning result, and performing fine positioning on the corresponding coarse positioning area through a second template containing only the to-be-detected Mark point; calculating a matching score of each to-be-detected Mark point according to the coarse positioning result and the fine positioning result, sorting the matching scores, and selecting a to-be-detected Mark point with the highest score as a target Mark point for accurate positioning. The method can solve the problem that a traditional Mark point positioning method adopts single template matching calculation, and error positioning is prone to occur in the case that a Mark point and a non-Mark point background are very similar.

Description

Technical Field

[0001] This invention relates to the field of optical inspection technology, and in particular to a wafer inspection mark point positioning method, a wafer inspection mark point positioning device, and a computer-readable storage medium. Background Technology

[0002] In wafer inspection, capturing only one image is sometimes insufficient to reveal all defects. Therefore, multiple images are captured, and the defect results from each image are merged after inspection to obtain the final result. During the merging process, the same mark point from multiple images is required; therefore, the detection of this mark point is crucial to the accuracy of the final result.

[0003] Existing mark point localization methods primarily rely on single-template matching, using a single template matching algorithm to determine the location of the mark point based on the highest matching score. However, in certain types of wafer inspection, the backgrounds of mark points and non-mark points are very similar. Since template matching algorithms consider the similarity of all pixels, even similar backgrounds can lead to very high matching scores, easily resulting in incorrect localization. To prevent incorrect localization, a matching score threshold is sometimes added; if the score is less than a set threshold, the found mark point is considered invalid. However, this threshold is a fixed value, which may be suitable for the current location but become too large for multiple test images from different angles, causing the mark point to be filtered out. In other words, optimizations introduced to handle incorrect localization may result in correct localizations being filtered out. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a wafer inspection Mark point positioning method, a wafer inspection Mark point positioning device, and a computer-readable storage medium. These methods can solve the problem that traditional Mark point positioning methods, which use single-template matching calculations, are prone to mispositioning when the backgrounds of Mark points and non-Mark points are very similar.

[0005] On one hand, embodiments of the present invention provide a wafer inspection Mark point localization method, comprising: acquiring all image frames under the same index of a wafer inspection image; performing coarse localization by using a first template covering the information surrounding the Mark point to be tested and the corresponding image frames; cropping a coarse localization area based on the coarse localization result; and performing fine localization by using a second template containing only the Mark point to be tested and the corresponding coarse localization area; calculating a matching score for each Mark point to be tested based on the coarse localization result and the fine localization result; sorting the matching scores; and selecting the Mark point to be tested with the highest score as the target Mark point for accurate localization.

[0006] In one embodiment of the present invention, the step of performing coarse localization by using a first template covering information around the target Mark point and the corresponding image includes: performing coarse localization matching calculation after downsampling the image and the first template, so as to improve the speed of coarse localization matching.

[0007] In one embodiment of the present invention, before performing image alignment based on the overlapping area between multiple grain detection images, the method further includes: selecting an alignment reference point and obtaining the grain detection image in which it is located as a reference image, and performing image alignment of the other grain detection images based on the reference image.

[0008] In one embodiment of the present invention, all the acquired image images have the same field of view. After coarse localization is performed between the first template covering the information around the Mark point to be tested and the corresponding image image, the method further includes: using the positional deviation between the Mark points of each image image after coarse localization as a test condition for judgment; and adding the Mark points that satisfy the preset positional deviation to the coarse localization candidate point sequence.

[0009] In one embodiment of the present invention, after determining the positional deviation between the Mark points of each of the coarsely located images as a test condition, the method further includes: establishing a Region of Interest (ROI) based on the Mark points that satisfy the preset positional deviation and the prior positional relationship between each of the images; performing coarse positioning again within the ROI based on the first template, and adding the Mark points that satisfy the preset positional deviation to the coarse positioning candidate point sequence.

[0010] In one embodiment of the present invention, after determining the positional deviation between the Mark points of each of the coarsely located images as a test condition, the method further includes: setting a minimum number threshold for the number of coarsely located candidate points, and exiting coarse positioning when the number of coarsely located candidate points reaches the minimum number threshold.

[0011] In one embodiment of the present invention, the step of performing fine positioning by using a second template containing only the Mark point to be tested and the corresponding coarse positioning region includes: calculating the finely positioned Mark point position information; and converting the Mark point position information onto the overall wafer inspection image based on the finely positioned Mark point position information plus the coarse positioning Mark point position information, and in combination with the downsampling sampling factor.

[0012] On the other hand, this invention proposes a wafer inspection Mark point positioning device, comprising: a coarse positioning module, used to acquire all image images under the same index of a wafer inspection image, and perform coarse positioning by using a first template covering the information surrounding the Mark point to be tested and the corresponding image images; a fine positioning module, used to crop out a coarse positioning area based on the coarse positioning result, and perform fine positioning by using a second template containing only the Mark point to be tested and the corresponding coarse positioning area; and a target Mark point selection module, used to calculate the matching score of each Mark point to be tested based on the coarse positioning result and the fine positioning result, sort the matching scores, and select the Mark point to be tested with the highest score as the target Mark point for accurate positioning.

[0013] In one embodiment of the present invention, the wafer inspection Mark point positioning device further includes: a deviation inspection module, used to judge the positional deviation between the Mark points of each of the screen images after coarse positioning as an inspection condition; and to add the Mark points that meet the preset positional deviation to the coarse positioning candidate point sequence.

[0014] In one embodiment of the present invention, the wafer inspection Mark point positioning device further includes: a Region of Interest (ROI) establishment module, used to establish an ROI region based on the Mark points that satisfy the preset position deviation and the prior positional relationship between each of the image images; to perform coarse positioning again in the ROI region based on the first template, and to add the Mark points that satisfy the preset position deviation to the coarse positioning candidate point sequence.

[0015] In another aspect, embodiments of the present invention provide a computer-readable storage medium storing computer-executable instructions for performing the wafer inspection Mark point positioning method as described in any of the above embodiments.

[0016] As can be seen from the above, the solution conceived by this invention, compared with the prior art, can have one or more of the following beneficial effects:

[0017] (1) Mark point localization is performed on the wafer inspection image using two templates. One template image, containing information about the surrounding area of ​​the mark point, is used for coarse localization, while the other template image, containing only the mark point, is used for fine localization. This improves the accuracy of mark point localization and effectively enhances the performance of wafer inspection images. When the backgrounds of Mark points and non-Mark points are very similar, a single template matching method is used. The calculation process can easily lead to mislocation problems. ;

[0018] (2) By establishing prior knowledge through the positional relationship between multiple images under the same index, it is only necessary to find the Mark points of some images during the localization process. These Mark points can be used to find the Mark points that were missed in other images, thus improving the robustness of the algorithm.

[0019] (3) For the missing Mark points, by using the Mark coarse positioning information of the successfully positioned image and combining the position constraints, the region of interest is captured near the successfully positioned Mark point, and coarse positioning is re-established in the region of interest. If successful, it is also added to the coarse positioning candidate point sequence. When the image that failed coarse positioning is matched and positioned again, the matching threshold will be dynamically reduced, which can effectively solve the problem of missing Mark points caused by the fixed threshold and improve the positioning accuracy.

[0020] (4) By setting a limit on the number of candidate points, the positioning ends when the number of candidate points reaches the threshold, which can effectively solve the problem of long judgment time caused by too many candidate Mark points and improve the positioning speed.

[0021] Other aspects of the invention will become apparent from the following detailed description with reference to the accompanying drawings. However, it should be understood that the drawings are for illustrative purposes only and not as a limitation of the scope of the invention. It should also be understood that, unless otherwise indicated, the drawings are not necessarily drawn to scale; they are merely intended to conceptually illustrate the structures and processes described herein. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 A flowchart of a wafer inspection mark point positioning method provided in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram illustrating the specific execution steps of a wafer inspection mark point positioning method provided in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of a wafer inspection mark point positioning device provided in an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of the structure of a computer-readable storage medium provided in an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures

[0028] S1 to S3: Steps in the wafer inspection Mark point positioning method;

[0029] 20: Wafer inspection Mark point positioning device; 201: Coarse positioning module; 202: Fine positioning module; 203: Target Mark point selection module;

[0030] 40: Computer-readable storage medium. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described with reference to the accompanying drawings and embodiments.

[0032] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments, and should all fall within the protection scope of the present invention.

[0033] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are applicable in distinguishing similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or applicable to such processes, methods, products, or apparatus.

[0034] It should also be noted that the division of multiple embodiments in this invention is only for the convenience of description and should not constitute a special limitation. Features in various embodiments can be combined and referenced in each other without contradiction.

[0035] [First Embodiment]

[0036] like Figure 1 As shown, the first embodiment of the present invention proposes a wafer inspection Mark point localization method, which includes the following steps: Step S1, acquiring all image images under the same index of the wafer inspection image, and performing coarse localization by using a first template covering the information around the Mark point to be tested and the corresponding image images; Step S2, cropping out the coarse localization area based on the coarse localization result, and performing fine localization by using a second template containing only the Mark point to be tested and the corresponding coarse localization area; Step S3, calculating the matching score of each Mark point to be tested based on the coarse localization result and the fine localization result, sorting the matching scores, and selecting the Mark point to be tested with the highest score as the target Mark point for accurate localization.

[0037] In step S1, multiple inspection images of the wafer to be inspected are captured using a device such as a camera, and the host computer software acquires these multiple serialized wafer inspection images. Since multiple images are often needed for the same area in wafer inspection, the acquired multiple wafer inspection images are, for example, divided into multiple indices, with each index corresponding to all images of its inspection area. For all images under the same index, coarse localization is performed, for example, using a first template covering the information surrounding the Mark point to be tested and the corresponding image. The host computer mentioned here can be, for example, a personal computer, handheld device, portable device, tablet device, multiprocessor system, microprocessor-based system, editable consumer electronics device, network PC, minicomputer, mainframe computer, or a distributed computing environment including any of the above systems or devices, etc.

[0038] In one implementation, without affecting the positioning results, for example, by downsampling the image and the first template before performing coarse positioning matching calculation, the speed of coarse positioning matching can be further improved.

[0039] Combination Figure 2 As shown, if all images under the current index are successfully matched in coarse localization, the corresponding Mark point is added to the candidate point sequence. In one implementation, the field of view remains constant during the capture of multiple images. Based on this known information, it can be ensured that the positional deviation of Mark points between multiple images is very small. Therefore, for example, the positional deviation between Mark points of each image after coarse localization is used as a test condition, and Mark points that meet the preset positional deviation are added to the coarse localization candidate point sequence. In this way, by establishing prior knowledge through the positional relationship between multiple images under the same index, the localization process only needs to find the Mark points of some images, and these Mark points can be used to find the Mark points that were missed in other images, thus improving the robustness of the algorithm.

[0040] Furthermore, if coarse localization fails in a certain frame, the coarse localization information of the Mark points in frames that meet the preset position deviation (i.e., have been successfully localized) can be used, combined with the positional constraints of each frame, to extract the Region of Interest (ROI) near the successfully localized Mark points. By re-coarsing within the ROI, if successful, it is added to the coarse localization candidate point sequence. This ensures that when frames that failed coarse localization are matched again, the matching threshold dynamically decreases, effectively solving the omission problem caused by a fixed threshold and improving localization accuracy.

[0041] In one implementation, a minimum threshold for the number of coarse positioning candidate points is set. When the number of coarse positioning candidate points reaches this minimum threshold, coarse positioning is terminated. This effectively solves the problem of long judgment time caused by an excessive number of candidate Mark points, thus improving the Mark point positioning speed.

[0042] In step S2, for example, the host computer software cuts out the coarse positioning area based on the coarse positioning result, and performs fine positioning by using a second template containing only the Mark points to be tested and the corresponding coarse positioning area. Specifically, since the matching calculation is already performed within a small area, downsampling is not required, and the speed is already fast. It should be noted that the Mark point position information calculated in this step is the starting point relative to the coarse positioning result. Therefore, when converting it to the overall wafer inspection image, for example, the Mark point position information is converted to the overall wafer inspection image by adding the coarse positioning Mark point position information to the fine positioning Mark point position information and combining the downsampling sampling factor.

[0043] In step S3, the score for each candidate Mark point is calculated based on the coarse and fine localization results. For example, the score for each Mark point is the sum of the coarse localization matching score from step S1 and the fine localization matching score from step S2. The matching scores are then sorted, and the Mark point with the highest score is selected as the target Mark point for accurate localization. It is worth noting that the final score for each candidate Mark point is, for example, the sum of the localization scores for each frame, rather than depending solely on a single frame; this improves the algorithm's stability.

[0044] In summary, the wafer inspection mark point localization method proposed in this invention uses two templates to locate mark points in the wafer inspection image. One template, a larger one containing information about the surrounding area of ​​the mark point, is used for coarse localization, while the other, a smaller template containing only the mark point, is used for fine localization. This improves the accuracy of mark point localization and effectively addresses the problem of erroneous localization caused by using single-template matching calculations when the backgrounds of mark points and non-mark points are very similar. Furthermore, by establishing prior knowledge based on the positional relationships between multiple images under the same index, the localization process only needs to find the mark points in some of the images to identify missed marks in other images. Mark points improve the robustness of the algorithm. For missed mark points, the algorithm utilizes the coarse positioning information of the mark points from successfully located images, combined with positional constraints, to extract the region of interest near the successfully located mark points. Coarse positioning is then performed again within the region of interest, and if successful, it is added to the coarse positioning candidate point sequence. This allows the matching threshold to dynamically decrease when images that failed to be coarsely positioned are matched again, effectively solving the problem of missed mark points caused by a fixed threshold and improving positioning accuracy. By setting a limit on the number of candidate points, positioning ends when the number of candidate points reaches the threshold, effectively solving the problem of long judgment time caused by too many candidate mark points and improving positioning speed.

[0045] [Second Embodiment]

[0046] like Figure 3 As shown, the second embodiment of the present invention proposes a wafer inspection Mark point positioning device 20, which includes, for example, a coarse positioning module 201, a fine positioning module 202, and a target Mark point selection module 203.

[0047] The coarse positioning module 201 acquires all images under the same index of the wafer inspection image and performs coarse positioning using a first template that covers the information surrounding the Mark point to be tested and the corresponding image. The fine positioning module 202 crops out the coarse positioning area based on the coarse positioning result and performs fine positioning using a second template that contains only the Mark point to be tested and the corresponding coarse positioning area. The target Mark point selection module 203 calculates the matching score of each Mark point to be tested based on the coarse and fine positioning results, sorts the matching scores, and selects the Mark point to be tested with the highest score as the target Mark point for accurate positioning.

[0048] Furthermore, the wafer inspection Mark point positioning device 20 may also include, for example, a deviation inspection module 204, which is used to judge the positional deviation between the Mark points of each of the screen images after coarse positioning as an inspection condition; and to add the Mark points that meet the preset positional deviation to the coarse positioning candidate point sequence.

[0049] Furthermore, the wafer inspection Mark point positioning device 20 may also include, for example, a Region of Interest (ROI) establishment module, used to establish an ROI region based on the Mark points that satisfy the preset position deviation and the prior positional relationship between each of the image maps; to perform coarse positioning again within the ROI region based on the first template, and to add the Mark points that satisfy the preset position deviation to the coarse positioning candidate point sequence.

[0050] The wafer inspection mark point positioning method implemented by the wafer inspection mark point positioning device 20 disclosed in the second embodiment of the present invention is as described in the first embodiment above, and therefore will not be described in detail here. Optionally, each module and the other operations or functions described above are for implementing the method described in the first embodiment, and the beneficial effects of this embodiment are the same as those of the first embodiment above, and will not be repeated here for the sake of brevity.

[0051] [Third Embodiment]

[0052] like Figure 4 As shown, the third embodiment of the present invention provides a computer-readable storage medium 30. The computer-readable storage medium 40 is a non-volatile memory and stores computer-readable instructions. When the computer-readable instructions are executed by one or more processors, for example, the one or more processors execute the wafer inspection mark point positioning method described in the first embodiment. Specific methods can be referred to the method described in the first embodiment, and for simplicity, will not be repeated here. Furthermore, the beneficial effects of the computer-readable storage medium 40 provided in this embodiment are the same as those of the wafer inspection mark point positioning method provided in the first embodiment.

[0053] Furthermore, it is understood that the foregoing embodiments are merely illustrative examples of the present invention. Provided that the technical features do not conflict, the structure is not contradictory, and the purpose of the invention is not violated, the technical solutions of the various embodiments can be arbitrarily combined and used.

[0054] In the several embodiments provided by this invention, it should be understood that the disclosed systems, devices, and / or methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of units / modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or modules may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0055] The units / modules described as separate components may or may not be physically separate. The components shown as units / modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units / modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0056] Furthermore, in the various embodiments of the present invention, the functional units / modules can be integrated into one processing unit / module, or each unit / module can exist physically separately, or two or more units / modules can be integrated into one unit / module. The integrated unit / module described above can be implemented in hardware or in the form of hardware plus software functional units / modules.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for locating Mark points in wafer inspection, characterized in that, include: All images under the same index of the wafer inspection image are acquired, and coarse localization is performed by a first template that covers the information around the Mark point to be tested and the corresponding images. The coarse positioning area is cut out based on the coarse positioning result, and fine positioning is performed by using a second template containing only the Mark point to be measured and the corresponding coarse positioning area. The matching score of each of the Mark points to be tested is calculated based on the coarse and fine positioning results, and the matching scores are sorted. The Mark point with the highest score is selected as the target Mark point for accurate positioning. All the acquired image images have the same field of view. After coarse localization is performed using a first template covering information around the Mark point to be measured and the corresponding image image, the method further includes: The positional deviation between the Mark points of each of the images after coarse positioning is used as a test condition for judgment. The Mark points that meet the preset position deviation are added to the coarse positioning candidate point sequence; If coarse localization fails in a screen image, then based on the coarse localization information of the Mark points of other screen images that have successfully met the preset position deviation, and combined with the position constraints of each screen image, the region of interest is predicted in the failed screen image and coarse localization is performed again.

2. The wafer inspection mark point positioning method according to claim 1, characterized in that, The coarse localization using a first template encompassing information surrounding the target Mark point and the corresponding image includes: After downsampling the image and the first template, coarse positioning matching calculation is performed to improve the speed of coarse positioning matching.

3. The wafer inspection mark point positioning method according to claim 1, characterized in that, After determining the positional deviation between the Mark points of each of the coarsely positioned images as a verification condition, the method further includes: ROI regions are established based on the Mark points that satisfy the preset positional deviation and the prior positional relationships between the various image maps; Within the ROI area, coarse positioning is performed again based on the first template, and the Mark points that meet the preset position deviation are also added to the coarse positioning candidate point sequence.

4. The wafer inspection mark point positioning method according to claim 1, characterized in that, After determining the positional deviation between the Mark points of each of the coarsely positioned images as a verification condition, the method further includes: Set a minimum number threshold for the number of coarse positioning candidate points, and exit coarse positioning when the number of coarse positioning candidate points reaches the minimum number threshold.

5. The wafer inspection mark point positioning method according to claim 2, characterized in that, The fine positioning using a second template containing only the Mark point to be measured and the corresponding coarse positioning region includes: Calculate the precise location information of the Mark points; Based on the precise positioning Mark point location information plus the coarse positioning Mark point location information, and combined with the downsampling sampling factor, the Mark point location information is converted onto the overall wafer inspection image.

6. A wafer inspection mark point positioning device, used to perform the method as described in any one of claims 1-5, characterized in that, include: The coarse positioning module is used to acquire all image images under the same index of the wafer inspection image, and to perform coarse positioning by using a first template that covers the information around the Mark point to be tested and the corresponding image images. The fine positioning module is used to cut out the coarse positioning area based on the coarse positioning result, and perform fine positioning by using a second template containing only the Mark point to be tested and the corresponding coarse positioning area. The target Mark point selection module is used to calculate the matching score of each of the Mark points to be tested based on the coarse positioning result and the fine positioning result, sort the matching scores, and select the Mark point to be tested with the highest score as the target Mark point for accurate positioning.

7. The wafer inspection mark point positioning device according to claim 6, characterized in that, Also includes: The deviation inspection module is used to judge the positional deviation between the Mark points of each of the screen images after coarse positioning as an inspection condition. The Mark points that meet the preset position deviation are added to the coarse positioning candidate point sequence.

8. The wafer inspection mark point positioning device according to claim 7, characterized in that, Also includes: The ROI region establishment module is used to establish ROI regions based on the Mark points that satisfy the preset positional deviation and the prior positional relationships between the various image maps. Within the ROI area, coarse positioning is performed again based on the first template, and the Mark points that meet the preset position deviation are also added to the coarse positioning candidate point sequence.

9. A computer-readable storage medium, characterized in that, It stores a computer program executable by an access authentication device, which, when run on the access authentication device, causes the access authentication device to perform the steps of the method described in any one of claims 1-5.

Images