Wafer scanning image acquisition method and system

Abstract

This application discloses a method and system for acquiring wafer scanning images, relating to the field of semiconductor image acquisition. The method includes: irradiating a target wafer with multiple parallel illumination beams to form multiple linear light spots on the surface of the target wafer; simultaneously acquiring images of the multiple linear light spots using multiple linear array scanning imaging devices while controlling the movement of the target wafer, obtaining multiple scanned images of the target wafer, with one linear array scanning imaging device corresponding to one linear light spot; fusing the multiple scanned images to obtain a fused scanned image; and filtering and removing speckled pixels from the fused scanned image based on pixel value characteristics to obtain the target image. This application not only improves the image signal-to-noise ratio and imaging clarity but also ensures image acquisition stability, enabling higher precision, higher efficiency, and more robust wafer image acquisition.

Description

Technical Field

[0001] This application belongs to the field of semiconductor image acquisition, and in particular relates to a method and system for acquiring wafer scanning images. Background Technology

[0002] Wafer defect inspection is a critical step in the semiconductor manufacturing process. To achieve high-precision inspection, it is usually necessary to use an illumination laser to scan and image the wafer surface, thereby obtaining a high-resolution image for subsequent analysis. However, the laser source has high spatial coherence, which easily forms interference patterns on the surface of the inspected wafer, i.e., speckle noise. This not only affects image clarity but may also mask minute defects, reducing the accuracy and reliability of the inspection.

[0003] To address the speckle interference problem, several suppression methods have been proposed, such as adjusting optical conditions to reduce coherence. However, these methods typically affect imaging stability and efficiency, making it difficult to balance image quality and system performance.

[0004] Therefore, designing a wafer image acquisition method that can effectively reduce speckle interference without affecting the imaging process has become an urgent technical problem to be solved. Summary of the Invention

[0005] This application provides a method and system for acquiring wafer scanning images, which can effectively reduce speckle interference in wafer scanning images without affecting imaging.

[0006] A first aspect of this application provides a method for acquiring wafer scan images, including:

[0007] Multiple parallel illumination beams are irradiated onto the target wafer, forming multiple linear light spots on the surface of the target wafer;

[0008] During the process of controlling the movement of the target wafer, multiple linear array scanning imaging devices are used to simultaneously image and acquire multiple linear light spots to obtain multiple scan images of the target wafer. One linear array scanning imaging device corresponds to one linear light spot.

[0009] Multiple scanned images are fused to obtain a fused scanned image;

[0010] Based on the pixel value features in the fused scan image, speckle pixels are filtered out from the fused scan image to obtain the target image.

[0011] A second aspect of this application provides a wafer scanning image acquisition apparatus, comprising:

[0012] An illumination module is used to form multiple linear light spots on the surface of a target wafer, wherein the multiple linear light spots are obtained by irradiating the target wafer with multiple parallel illumination beams;

[0013] Multiple linear array scanning imaging devices are used to simultaneously image and acquire multiple linear light spots during the movement of the target wafer, obtain multiple scan images of the target wafer, and send the multiple scan images to an image processing device. One linear array scanning imaging device corresponds to one linear light spot.

[0014] An image processing device is used to fuse multiple scan images sent by multiple linear scan imaging devices to obtain a fused scan image;

[0015] And it is used to filter and remove speckle pixels from the fused scan image based on the pixel value features in the fused scan image to obtain the target image.

[0016] A third aspect of the embodiments of this application provides an electronic device, the device comprising: a memory and a program or instructions stored in the memory and executable on a processor, wherein the program or instructions, when executed by the processor, implement the method provided in any of the embodiments of this application described above.

[0017] A fourth aspect of the embodiments of this application provides a readable storage medium on which a program or instructions are stored, and when the program or instructions are executed by a processor, they implement the method provided by any aspect of the embodiments of this application described above.

[0018] A fifth aspect of the embodiments of this application provides a computer program product in which instructions, when executed by a processor of an electronic device, cause the electronic device to perform the method provided in any of the embodiments of this application described above.

[0019] The wafer scanning image acquisition method provided in this application addresses the speckle interference problem caused by the coherence of the illumination source during wafer defect detection. It involves illuminating the target wafer with multiple parallel illumination beams, forming multiple linear light spots on the wafer surface. During wafer movement, multiple linear array scanning imaging devices are used to simultaneously acquire images of each linear light spot region, enabling high-throughput imaging by obtaining multiple spatiotemporally aligned scanning images per unit time. Further fusion processing of these multiple scanning images effectively reduces random interference caused by speckle and improves the image signal-to-noise ratio. Based on the fused image, speckle pixels generated by coherent light interference are removed according to pixel value characteristics, ultimately obtaining a target image with higher clarity and less interference, thereby achieving higher precision and stronger stability in wafer image acquisition. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic flowchart of a wafer scanning image acquisition method provided in one embodiment of this application;

[0022] Figure 2 A schematic diagram illustrating the wafer scanning process provided in an embodiment of this application is shown.

[0023] Figure 3 A schematic diagram illustrating the wafer image imaging process provided in an embodiment of this application is shown.

[0024] Figure 4 A schematic diagram illustrating the beam splitting process of the beam splitting device provided in the embodiments of this application is shown.

[0025] Figure 5 The illustration shows a schematic example of the image fusion method provided in the embodiments of this application.

[0026] Figure 6 A schematic diagram illustrating the speckle removal effect provided in the embodiments of this application is shown.

[0027] Figure 7 A schematic diagram of a wafer scanning image acquisition system provided in an embodiment of this application is shown.

[0028] Figure 8 A schematic diagram of the architecture of a wafer scanning image acquisition system proposed in an embodiment of this application is shown.

[0029] Figure 9 An optical path diagram for dark field detection according to an embodiment of this application is shown.

[0030] Figure 10 This is a schematic diagram of an electronic device provided in one embodiment of this application. Detailed Implementation

[0031] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are intended only to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0032] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus 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 apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0033] It should be noted that the acquisition, storage, use, and processing of data in the technical solution of this application all comply with the relevant provisions of national laws and regulations. In the embodiments of this application, certain existing industry solutions such as software, components, and models may be mentioned. These should be considered exemplary, intended only to illustrate the feasibility of implementing the technical solution of this application, and do not imply that the applicant has already used or necessarily used such solutions.

[0034] First, the terms and concepts involved in one or more embodiments of this application will be explained.

[0035] A wafer is a silicon wafer that has undergone specific processing techniques, on which a series of chip manufacturing processes can be carried out, such as photolithography, etching, and doping.

[0036] Wafer inspection is the process of checking for defects on the surface of a wafer during semiconductor manufacturing.

[0037] Light source coherence refers to the phase relationship between different light waves emitted by a light source. When a light source has strong coherence, the phase consistency between light waves is high, which causes interference when the light waves illuminate the surface of an object, resulting in a speckle effect that affects image quality. Light sources with strong coherence (such as lasers) typically induce speckle phenomena significantly, while light sources with weak coherence (such as white light) produce less speckle effects.

[0038] Speckle effect is the optical interference phenomenon caused by surface inhomogeneities when a laser or other coherent light source illuminates a sample surface. Speckle effects produce unevenly bright and dark spots in the image, affecting image quality and detection accuracy.

[0039] In the field of semiconductor integrated circuit technology, with the continuous advancement of semiconductor technology and the increasing complexity of manufacturing processes, the number of wafer defects has also increased. To ensure the quality of semiconductor products, rigorous defect inspection of wafers is required during the manufacturing process. Commonly used inspection methods include bright-field inspection and dark-field inspection, which identify defects under different lighting conditions.

[0040] However, in the process of wafer defect detection, the use of coherent light sources such as lasers for illumination causes speckle effect due to the coherence of the light source. This produces uneven light spots in the image, affecting image quality and detection accuracy. Especially in the detection of small defects, speckle effect can significantly reduce the accuracy of detection.

[0041] Currently, although some methods have been attempted to reduce speckle effect by adjusting the light source or improving the optical path design, the results are still unsatisfactory. Moreover, these methods often suffer from problems such as insufficient imaging stability, increased system complexity, or decreased acquisition efficiency, making it difficult to balance imaging quality and system performance in practical applications.

[0042] In view of this, this application provides a wafer scanning image acquisition method and system. The wafer scanning image acquisition method provided in this application involves deploying multiple linear scan cameras and simultaneously acquiring multiple spatiotemporally aligned scanning images during wafer movement. These acquired images are then fused to reduce the randomness of speckle interference. Furthermore, abnormal pixels corresponding to speckle are identified and removed based on pixel value features in the fused image, thereby obtaining a target image with less interference and clearer details. This method not only improves the image signal-to-noise ratio and imaging clarity but also balances acquisition throughput and system stability, enabling higher precision, higher efficiency, and more robust wafer image acquisition. It is suitable for semiconductor manufacturing scenarios with high inspection quality requirements.

[0043] For example, the wafer scanning image acquisition method provided in this application embodiment can be applied to the production line of a semiconductor manufacturing company for defect detection and classification of semiconductor devices generated during the production process. In practical applications, the wafer scanning image acquisition method provided in this application embodiment scans the wafer to be inspected and performs speckle reduction processing on the scanned image to obtain a target wafer scanning image with less interference and clearer details.

[0044] It should be noted that the application scenarios described in the above embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0045] The wafer scanning image acquisition method provided in the embodiments of this application is described below. In practical applications, the entity executing the wafer scanning image acquisition method in the embodiments of this application can be an electronic device.

[0046] Figure 1 A schematic flowchart of a wafer scanning image acquisition method according to an embodiment of this application is shown. Figure 1 As shown, the method includes steps S110 to S140.

[0047] S110. Multiple parallel illumination beams are directed onto the target wafer to form multiple linear light spots on the surface of the target wafer.

[0048] An illumination beam is a light source output used to illuminate a target wafer to achieve image acquisition.

[0049] For example, the illumination beam is typically a laser beam, which is suitable for high-precision scanning imaging tasks due to its high brightness and spatial coherence.

[0050] The target wafer refers to the wafer to be inspected or scanned.

[0051] For example, the target wafer is placed at a fixed position on the workpiece stage and can move with the workpiece stage during the scanning process.

[0052] A linear spot is a strip-shaped bright area formed on the wafer surface by an illumination beam, having a certain length and narrow width. Each linear spot corresponds to an imaging channel used to acquire local image information of the wafer surface.

[0053] Understandably, traditional wafer inspection methods typically use only a single illumination beam to irradiate the target wafer, forming a single linear spot on its surface. This is then combined with a linear scan camera to complete image acquisition. However, due to limitations in single-channel acquisition speed and image throughput, the imaging efficiency is relatively low.

[0054] To improve acquisition efficiency, this application sets up multiple parallel illumination beams to simultaneously irradiate the target wafer, forming multiple parallel linear light spots on its surface.

[0055] It is important to emphasize that multiple illumination beams must be parallel to each other to ensure that the linear light spots are evenly distributed on the wafer surface and that the illumination angles are consistent. This avoids image distortion, uneven brightness, or imaging errors caused by differences in incident direction, ensuring good geometric consistency and comparability of subsequent images. This enables multi-channel synchronous acquisition, laying the foundation for subsequent image fusion and speckle suppression.

[0056] S120. During the process of controlling the movement of the target wafer, multiple linear array scanning imaging devices are used to synchronously image and acquire multiple linear light spots to obtain multiple scan images of the target wafer.

[0057] Linear scan imaging equipment refers to an imaging device that acquires images of the illuminated area line by line, and is suitable for high-precision imaging when the target is moving continuously.

[0058] The imaging principle of a linear array scanning imaging device is as follows: it receives reflected light signals from the surface of the target wafer sequentially along a fixed direction, and combines this with information on the positional changes of the target wafer in the moving direction to gradually reconstruct a complete two-dimensional image of the target wafer, thereby achieving high-precision imaging.

[0059] For example, in this application, the linear scan imaging device preferably employs a time-delay integration (TDI) camera. Hereinafter referred to simply as a TDI camera.

[0060] TDI cameras significantly improve imaging sensitivity and signal-to-noise ratio by setting multiple photosensitive units along the direction of movement of the object being measured and performing time integration of photoelectric signals during image reading. They are particularly suitable for imaging low-reflectivity or high-speed moving targets such as wafers.

[0061] Corresponding to the multiple linear light spots, this application deploys multiple linear scanning imaging devices (TDI cameras), that is, one linear light spot corresponds to one linear scanning imaging device. In other words, each linear scanning imaging device is dedicated to acquiring the reflection image of the corresponding light spot area.

[0062] It should be understood that the reason for designing multiple TDI cameras is that TDI cameras have a limited effective depth of field. If multiple linear light spots are simultaneously imaged on the same camera in a non-orthogonal (e.g., oblique incidence) manner, some light spots may exceed the depth of field range, resulting in image blurring.

[0063] Figure 2 A schematic diagram illustrating the wafer scanning process provided in an embodiment of this application is shown. Figure 2 In the example shown, the target wafer moves in the direction indicated by the arrow during the scanning process, forming two linear light spots on its surface, namely spot 1 and spot 2. To achieve high-quality imaging of the area covered by these two light spots, two TDI cameras are set up: TDI-1 and TDI-2. TDI-1 is used to collect the reflected light from spot 1 and form the corresponding linear scan image, while TDI-2 is used to collect the reflected light from spot 2 and generate a scan image of another channel.

[0064] Figure 3 This illustration shows a schematic example of the wafer image imaging process provided in an embodiment of this application. Figure 3 As shown, since the position of the light spot remains constant relative to the wafer during the movement of the wafer, and combined with the linear array imaging characteristics of the TDI camera which has good adaptability to moving objects, TDI-1 and TDI-2 can achieve synchronous acquisition of the reflected light of light spot 1 and light spot 2 based on receiving synchronous position information, thereby obtaining a spatiotemporally aligned multi-channel scanning image.

[0065] The example above employs a dual beam-splitting structure, sequentially splitting the reflected beam from the target wafer surface into multiple optical paths, which are then guided to different TDI cameras for imaging. Each TDI camera can acquire images of the same target area, enabling multiple exposures and multi-channel synchronous acquisition of the same target image.

[0066] Based on this, since TDI cameras have a large field of view (FOV) along the integration direction (i.e., the scanning direction), which is typically much larger than the width (W) of the linear spot formed by a single laser illumination beam, multiple separate linear laser spots can be accommodated within the field of view of a single objective lens, allowing for simultaneous multi-point exposure and imaging. This structure can fully utilize the spatial redundancy of the TDI camera along the integration direction, achieving a dual improvement in imaging efficiency and image quality.

[0067] Theoretically, the maximum number of light spots N that can be set in the system can be estimated by the following formula:

[0068] N = FOV / W;

[0069] in,

[0070] FOV represents the field of view of the objective lens in the integration direction of a TDI camera;

[0071] W represents the width of a single laser spot.

[0072] Theoretically, without the interference of overlapping light spots, multiple linear light spots can be arranged within the FOV of a TDI camera. Each light spot is split by a corresponding optical path and sent to an independent TDI camera for acquisition, thereby realizing multi-channel parallel imaging.

[0073] In some embodiments, multiple linear scan imaging devices are respectively positioned in the emission direction of the reflected light generated by the corresponding linear light spots to ensure that each light spot can be independently acquired under optimal imaging conditions, thereby obtaining a multi-channel image with uniform quality.

[0074] In this embodiment, by setting multiple linear array scanning imaging devices in the emission direction of the reflected light generated by the corresponding linear light spots, the reflected light can be directly received and imaged by their respective imaging devices without beam splitting. This simplifies the optical path structure, reduces the use of optical components, lowers system cost and energy consumption, and avoids uneven energy distribution caused by beam splitting, which is beneficial to improving the signal-to-noise ratio and stability of imaging in each channel.

[0075] Conversely, in other embodiments, a beam splitter can be used to spatially split the reflected light generated by multiple linear light spots, and guide the multiple reflected light beams to the corresponding linear array scanning imaging devices for imaging acquisition, thereby achieving multi-channel synchronous imaging.

[0076] A beam splitter is an optical device that separates and guides reflected light from multiple illumination areas according to spatial direction or wavelength characteristics.

[0077] For example, the beam splitter can be a beam splitter prism, which can guide multiple reflected beams to their respective imaging devices along a predetermined path.

[0078] Figure 4 A schematic diagram illustrating the beam splitting process achieved by a beam splitter is shown. Figure 4 The example shown illustrates a beam splitter with two functional films on its surface: a high-reflectivity reflective film @355 and a high-transmittance antireflective film @355.

[0079] High reflectivity reflective film @355 refers to an optical thin film with high reflectivity for light with a center wavelength of 355nm, capable of reflecting most of the incident light in the 355nm band.

[0080] High transmittance antireflective coating @355 refers to an optical coating that has high transmittance for light in the same wavelength band and is used to reduce interface reflection loss and improve light transmission efficiency.

[0081] In practical applications, such as Figure 4 As shown, when parallel incident light rays strike this beam splitter, a portion of the light rays first contact the side with the high-transmittance antireflective coating @355, allowing most of the light energy to pass through smoothly. Subsequently, when encountering the interface with the high-reflectivity reflective coating @355, the 355nm light rays meeting specific incident angle conditions are efficiently reflected and emitted in different directions, thus achieving the separation of light rays in the same wavelength band. This structure can be used to spatially distribute light energy from the same direction, adapting to multiple optical path systems, and also facilitating multi-channel synchronous illumination or imaging.

[0082] In this embodiment, a beam splitter is used to spatially split the reflected light generated by multiple linear light spots, and the split reflected light is guided to the corresponding linear array scanning imaging device for imaging acquisition. This achieves spatial decoupling of multiple imaging paths, allowing each linear array scanning device to independently receive and image the corresponding light spot reflection signal. This effectively improves the imaging efficiency and synchronous acquisition accuracy of the system, reduces imaging path interference, and is beneficial for subsequent image fusion processing and high-quality image reconstruction.

[0083] Therefore, it can be seen that using multiple TDI cameras can achieve multi-channel synchronous imaging of the target wafer, thereby acquiring multiple scan images.

[0084] S130. Perform fusion processing on multiple scanned images to obtain a fused scanned image.

[0085] This step involves fusing multiple scanned images acquired by a TDI camera to integrate image information from different imaging channels and construct a fused scanned image with better spatial consistency and a higher signal-to-noise ratio.

[0086] Since each linear array imaging device acquires images of the same target wafer at different locations or under different lighting conditions, these images have a high degree of correspondence in space and time. Therefore, based on the pixel value features, structural information, or frequency domain characteristics of the images, fusion algorithms such as weighted averaging, principal component analysis, sparse representation, image registration, and reconstruction can be used for processing.

[0087] In one implementation, the pixel values ​​at corresponding locations in multiple scanned images are weighted and summed to generate a fused image. The weights can be dynamically adjusted based on the brightness uniformity, signal-to-noise ratio (SNR), or texture sharpness of local regions in each image, allowing images with high SNR and sharp textures to contribute more, thus retaining more effective information in the fusion result and suppressing random speckle interference. This method is computationally efficient and suitable for high-throughput image processing scenarios with strict time requirements.

[0088] In one implementation, an image registration algorithm can be used to align scanned images from multiple channels at the sub-pixel level, ensuring accurate overlap of structural details. The aligned scanned images are then superimposed pixel-wise to obtain a fused image. This method effectively reduces structural offset between multiple images, improves the consistency and clarity of the fused image, and the direct superposition method is simpler and more efficient than weighted fusion.

[0089] S140. Based on the pixel value features in the fused scan image, filter and remove speckle pixels from the fused scan image to obtain the target image.

[0090] Pixel value features refer to information used to characterize the local content of an image, starting from the grayscale or color value of each pixel in the fused scanned image and combining its distribution characteristics in spatial, statistical, or structural dimensions.

[0091] The target image refers to the fused wafer scan image result obtained after speckle removal processing, which is clearer and has less interference.

[0092] This step utilizes the structural characteristics of the fused image to effectively distinguish speckled pixels from real image information, thereby improving imaging quality and the accuracy of subsequent analysis.

[0093] In one implementation, statistical measures such as the mean, variance, and gradient of the grayscale of each pixel's neighborhood in the fused image can be calculated. These parameters, combined with a set threshold, are used to determine whether a pixel represents high-frequency speckle noise. Pixels identified as speckle are then replaced or interpolated to preserve the continuity of the image structure. This method is simple to implement, suitable for real-time processing scenarios, and effectively balances noise reduction with image detail preservation.

[0094] In summary, to address the speckle interference problem caused by highly coherent light sources in wafer inspection, the wafer scanning image acquisition method proposed in this application illuminates the target wafer with multiple parallel illumination beams, forming multiple linear light spots on the wafer surface. Due to the unique optical properties of wafer materials, traditional single-channel imaging is difficult to effectively suppress speckle noise caused by coherent light sources. However, this method utilizes multiple linear array scanning imaging devices to simultaneously acquire each linear light spot region during wafer movement, enabling the acquisition of multiple spatiotemporally aligned scanning images per unit time, achieving high-throughput imaging. Furthermore, the fusion processing of multiple scanning images effectively reduces the random interference of speckle caused by the microstructure of the wafer surface, improving the image signal-to-noise ratio. Based on the fused image, speckle pixels generated by coherent light interference are removed based on pixel value characteristics, ultimately obtaining a target image with higher clarity and less interference, thereby achieving higher precision and stronger stability in wafer image acquisition.

[0095] Based on the foregoing introduction of the proposed solution, it can be summarized and emphasized that, in order to accurately identify and eliminate speckle pixels with a certain regularity generated by coherent light interference, multiple imaging channels in this application's method must employ the same or similar imaging optical systems and operating modes to acquire wafer surface images. This is the system foundation of this application's method. Because the formation mechanism of speckle noise is directly related to the coherence characteristics of the wafer surface structure and the illumination light field, it is necessary to ensure that the imaging conditions of each channel are approximately consistent in order to ensure the spatiotemporal predictability of the speckle pattern, thereby effectively distinguishing between real wafer surface features and speckle interference through multi-image fusion.

[0096] In one embodiment, step S110 may include the following steps:

[0097] S111. Acquire the position information of the target wafer during its movement and simultaneously send the position information to multiple linear array scanning imaging devices.

[0098] Location information refers to numerical data used to characterize the position of a target wafer at a certain moment on its movement trajectory.

[0099] For example, location information can be represented as one-dimensional or two-dimensional coordinates, or it can be combined with timestamps to form location-time pairs.

[0100] In one implementation, high-precision displacement detection devices such as encoders, interferometers, or laser rangefinders can be used to acquire the wafer's position signal in real time during movement. To ensure consistency in image acquisition of the same wafer position by multiple linear scanning imaging devices, a signal distributor or bus replication mechanism can be further employed to copy the acquired position signal into multiple equivalent copies in real time and send them to each imaging device, thereby achieving synchronous sharing of position information among the channels.

[0101] S112. Using multiple linear array scanning imaging devices, reflective images corresponding to multiple linear light spots are acquired synchronously according to position information to obtain multiple scan images that are spatially and temporally aligned.

[0102] When performing image reconstruction, linear scanning imaging devices such as TDI cameras need to combine the displacement information of the target in the direction of movement to determine the timing of image acquisition for each row. By introducing shared position information, all linear scanning imaging devices can simultaneously start image acquisition when the target wafer moves to a specific position, based on the same position reference.

[0103] Since each device receives a synchronization signal at the same time and the same position of motion, the image fragments captured by each camera correspond to the same area on the wafer, only from reflection responses under different illumination channels. This achieves accurate spatial and temporal alignment of the images, resulting in multiple spatiotemporally aligned scan images.

[0104] In this embodiment, by acquiring the position information of the target wafer during its movement and simultaneously sending this information to multiple linear array scanning imaging devices, each imaging device can simultaneously acquire images based on the unified position information. This ensures that the multiple scanned images obtained are aligned in time and space, avoiding image misalignment and information deviation caused by asynchronous wafer movement or device acquisition delays, thereby improving the accuracy of image fusion and the imaging quality of the final image.

[0105] In one embodiment, the fusion method in step S130 may include any of the following:

[0106] S131. Calculate the average pixel value at the same pixel position of multiple scanned images, and determine the average pixel value as the pixel value of the fused scanned image at that pixel position.

[0107] Figure 5 A schematic diagram illustrating an image fusion method provided in this application embodiment is shown. In this example, scanned image 1 and scanned image 2 are synchronously acquired by TDI-1 and TDI-2 cameras during the movement of the target wafer, respectively. They have spatiotemporal alignment characteristics, meaning that pixels at the same location reflect the reflection information of the same physical point. This example uses the fusion method of step S131 to perform pixel-by-pixel fusion processing on scanned image 1 and scanned image 2.

[0108] Specifically, for each corresponding pixel location, the pixel values ​​from scanned image 1 and scanned image 2 are read separately, and their average value is calculated as the final pixel value of the fused scanned image at that pixel location. For example, for a certain pixel location (i, j), let the pixel value of scanned image 1 be P1(i, j) and the pixel value of scanned image 2 be P2(i, j), then the value of the corresponding pixel in the fused image is P(i, j) = (P1(i, j) + P2(i, j)) / 2. This process is repeated for all pixels to complete the fusion process, resulting in the fused scanned image.

[0109] S132. According to the preset weight, perform a weighted average calculation on the pixel values ​​of multiple scanned images at the same pixel position, and determine the weighted calculation result as the pixel value of the fused scanned image at that pixel position.

[0110] In this embodiment, multiple scanned images are fused to effectively suppress random noise and speckle interference, thereby improving the imaging signal-to-noise ratio and image quality. Specifically, by calculating the average pixel value at the same pixel position in multiple scanned images, or by performing a weighted average based on preset weights, the fused image achieves image enhancement while retaining effective information, thus obtaining a clearer and more stable target image, providing a reliable data foundation for subsequent detection and analysis.

[0111] In one embodiment, step S140 may include the following steps:

[0112] S141. Pixels in the fused scan image whose pixel values ​​are lower than a preset threshold are identified as speckle pixels.

[0113] The preset threshold is the pixel intensity boundary value used to distinguish between valid image signals and invalid speckle signals.

[0114] It should be understood that since speckle is usually a random and low-intensity image noise, pixels below a certain threshold can be marked and removed.

[0115] It should also be understood that the preset threshold can be obtained through historical sample data analysis, image comparison experiments, or empirical parameter optimization to achieve a better image purification effect, and this application does not limit this.

[0116] S142. Remove speckle pixels from the fused scan image to obtain the target image.

[0117] In one implementation, speckle pixels can be removed by replacing their values ​​with 0, thereby directly removing these low signal-to-noise ratio pixels from the image so that they no longer interfere with subsequent image analysis.

[0118] For example, the preset threshold can be set to 80. Figure 5 Taking the fused image shown as an example, after performing pixel mean fusion on scanned image 1 and scanned image 2, the resulting fused scanned image contains some low-intensity pixels. Next, pixels with a pixel value below 80 in the fused image are identified as speckle pixels, and their pixel values ​​are set to 0 to form the target image.

[0119] In this embodiment, by setting a pixel value threshold to identify and remove speckle regions with low signal-to-noise ratio, the imaging noise background is significantly reduced, the contrast and detail retention of the target image are improved, which is beneficial to the accuracy and stability of subsequent image analysis and defect detection.

[0120] Figure 6 A schematic example of the speckle removal effect is shown. From Figure 6 As can be seen, the real images of scanned image 1 and scanned image 2 contain a large number of randomly distributed low-intensity speckle signals. However, in the target image obtained after processing by the method of this application, speckle pixels have been effectively removed, the background is cleaner, the image structure is clearer, and the accuracy and robustness of subsequent defect identification and quality assessment are significantly improved.

[0121] Based on a wafer scanning image acquisition method, this application also provides specific embodiments of a wafer scanning image acquisition system.

[0122] Figure 7 A schematic diagram of a wafer scanning image acquisition system provided in an embodiment of this application is shown.

[0123] like Figure 7 As shown, the wafer scanning image acquisition system 1000 provided in this application embodiment may include the following parts.

[0124] The illumination module 1001 is used to form multiple linear light spots on the surface of the target wafer.

[0125] The multiple linear light spots are obtained by irradiating the target wafer with multiple parallel illumination beams.

[0126] Multiple linear array scanning imaging devices 1002 are used to simultaneously image and acquire multiple linear light spots during the movement of the target wafer, obtain multiple scan images of the target wafer, and send the multiple scan images to the image processing device 1003.

[0127] One linear array scanning imaging device corresponds to one linear light spot.

[0128] Image processing device 1003 is used to receive multiple scan images sent by multiple linear scan imaging devices 1002, perform fusion processing on the multiple scan images to obtain a fused scan image, and filter and remove speckle pixels from the fused scan image based on pixel value features in the fused scan image to obtain a target image.

[0129] For example, the image processing device 1003 may include an image fusion module and a speckle processing module.

[0130] The image fusion module is used to fuse multiple scanned images to obtain a fused scanned image.

[0131] The speckle processing module is used to filter and remove speckle pixels from the fused scan image based on the pixel value features in the fused scan image to obtain the target image.

[0132] In one embodiment, the image processing device 1003 can be a standalone image processing unit, such as an industrial computer or an image processing server; it can also be integrated into the line array scanning imaging device 1002 in an embedded form, thereby achieving a more compact system design and higher processing efficiency.

[0133] In one embodiment, the wafer scanning image acquisition system 1000 may include at least one beam splitter, which is used to spatially split the reflected light generated by multiple linear light spots so as to guide the multiple reflected light beams to the corresponding linear scan imaging devices for imaging acquisition.

[0134] Figure 8 A schematic diagram of the architecture of a wafer scanning image acquisition system proposed in an embodiment of this application is shown.

[0135] like Figure 8 As shown, the system includes four TDI cameras (TDI-1, TDI-2, TDI-3 and TDI-4), three beam splitters (denoted as A, B and C respectively), and a set of optical components, including a collection lens 1 and a zoom lens 2.

[0136] In this system, reflected light from the wafer surface first passes through converging lens 1, which focuses scattered or reflected light from multiple angles and positions into a relatively parallel beam, improving image quality and light flux utilization efficiency. The beam then continues through zoom lens 2, which dynamically adjusts the image magnification to adapt to the imaging needs of different wafer regions, ensuring the imaging system can flexibly handle different scale and resolution requirements.

[0137] The pre-processed beam first enters beam splitter A. Beam splitter A contains a high-reflectivity reflective film and a high-transmittance anti-reflective film to separate the beam's direction: part of the light propagates upwards, and the other part propagates to the right. Next, the upward-propagating beam reaches beam splitter B, which further splits it into two beams, reflecting them to the left and upwards respectively, guiding them to TDI-1 and TDI-2 for imaging. Similarly, the right-propagating beam reaches beam splitter C, which also further splits it into upward and rightward directions, guiding it to TDI-3 and TDI-4 for imaging.

[0138] This multi-level beam splitting and multi-channel imaging structure enables multiple distribution of the same reflected beam, allowing multiple TDI cameras to simultaneously acquire image information from the same target area, thereby improving the spatial coverage and data parallel processing capabilities of the imaging system. This architecture supports multi-channel, high-resolution wafer surface image acquisition, effectively enhancing the system's ability to detect minute defects and improving scanning efficiency and stability.

[0139] Figure 9 An optical path diagram for dark-field detection is shown, combining the wafer scanning image acquisition method and system proposed in this application. An illumination beam is emitted from a dark-field light source a, and after shaping / polarization / splitting / scanning operations, it reaches a reflecting mirror b, thereby illuminating the wafer surface on a displacement stage c. This causes surface defects to generate scattered light. Multiple imaging probes arranged at different angles (left, middle, and right paths) collect these scattered light signals, and images are acquired by cameras x, y, and z, respectively. Finally, the signals are transmitted to a processing module for defect identification and analysis, thus achieving high-precision dark-field detection of the wafer surface.

[0140] Based on a wafer scanning image acquisition method, this application also provides specific embodiments of an electronic device.

[0141] Figure 10 A schematic diagram of the hardware structure of the electronic device provided in an embodiment of this application is shown.

[0142] The electronic device may include a processor 7001 and a memory 7002 storing computer program instructions.

[0143] Specifically, the processor 7001 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0144] Memory 7002 may include mass storage for data or instructions. For example, and not limitingly, memory 7002 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 7002 may include removable or non-removable (or fixed) media. Where appropriate, memory 7002 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 7002 is non-volatile solid-state memory.

[0145] The processor 7001 reads and executes computer program instructions stored in the memory 7002 to implement any of the wafer scanning image acquisition methods in the above embodiments.

[0146] In one example, the electronic device may also include a communication interface 7003 and a bus 7004. Wherein, as... Figure 10 As shown, the processor 7001, memory 7002, and communication interface 7003 are connected through bus 7004 and complete communication with each other.

[0147] The communication interface 7003 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0148] Bus 7004 includes hardware, software, or both, that couples the components of the electronic device together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 7004 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, any suitable bus or interconnect is contemplated herein.

[0149] Furthermore, in conjunction with the image defect classification method in the above embodiments, this application embodiment can provide a computer storage medium for implementation. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the wafer scanning image acquisition methods in the above embodiments.

[0150] In addition, in conjunction with the wafer scanning image acquisition method in the above embodiments, this application embodiment can provide a computer program product for implementation. When the instructions in the computer program product are executed by the processor of an electronic device, the electronic device performs the wafer scanning image acquisition method provided by any aspect of the above embodiments of this application.

[0151] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0152] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0153] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0154] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0155] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for acquiring wafer scanning images, characterized in that, include: Multiple parallel illumination beams are irradiated onto the target wafer, forming multiple linear light spots on the surface of the target wafer; During the process of controlling the movement of the target wafer, multiple linear array scanning imaging devices are used to synchronously image and acquire the multiple linear light spots to obtain multiple scan images of the target wafer, with one linear array scanning imaging device corresponding to one linear light spot. The multiple scanned images are fused to obtain a fused scanned image; Based on the pixel value features in the fused scan image, speckle pixels are filtered out from the fused scan image to obtain the target image; The method of simultaneously imaging and acquiring the multiple linear light spots using multiple linear array scanning imaging devices includes: By using a dual beam splitting structure composed of at least two beam splitting devices, the reflected light generated by the multiple linear light spots is spatially split so that the multiple reflected light beams are guided to the corresponding linear array scanning imaging devices for imaging and acquisition. The method of simultaneously imaging and acquiring multiple linear light spots using multiple linear array scanning imaging devices to obtain multiple scanned images of the target wafer includes: The position information of the target wafer during its movement is acquired, and the position information is synchronously sent to the multiple linear array scanning imaging devices; Using the multiple linear array scanning imaging devices, the reflection images corresponding to the multiple linear light spots are acquired synchronously according to the position information to obtain the multiple scan images. The multiple scan images are multiple spatiotemporally aligned images corresponding to the reflection responses of the same area and different illumination channels on the target wafer.

2. The method according to claim 1, characterized in that, The multiple linear array scanning imaging devices are respectively positioned in the direction of emission of reflected light generated by the corresponding linear light spots.

3. The method according to any one of claims 1 to 2, characterized in that, The process of fusing the multiple scanned images to obtain a fused scanned image includes: Calculate the average pixel value at the same pixel location in the multiple scanned images, and determine the average pixel value as the pixel value of the fused scanned image at that pixel location; or; According to a preset weight, the pixel values ​​of the multiple scanned images at the same pixel position are weighted and calculated, and the weighted calculation result is determined as the pixel value of the fused scanned image at that pixel position.

4. The method according to claim 3, characterized in that, The step of filtering and removing speckle pixels from the fused scan image based on pixel value features to obtain the target image includes: Pixels in the fused scan image whose pixel values ​​are lower than a preset threshold are identified as speckle pixels; The target image is obtained by removing the speckle pixels from the fused scan image.

5. The method according to any one of claims 1 to 2, characterized in that, The linear array scanning imaging device is a time-delay integral linear array (TDI) camera.

6. A wafer scanning image acquisition system, characterized in that, include: An illumination module is used to form multiple linear light spots on the surface of a target wafer, wherein the multiple linear light spots are obtained by irradiating the target wafer with multiple parallel illumination beams; Multiple linear array scanning imaging devices are used to synchronously image and acquire multiple linear light spots during the movement of the target wafer, obtain multiple scan images of the target wafer, and send the multiple scan images to an image processing device. One linear array scanning imaging device corresponds to one linear light spot. An image processing device is used to perform fusion processing on the multiple scan images sent by the multiple linear scan imaging devices to obtain a fused scan image; and to filter and remove speckle pixels from the fused scan image based on pixel value features in the fused scan image to obtain a target image; Simultaneous imaging and acquisition of the multiple linear light spots using multiple linear array scanning imaging devices includes: By using a dual beam splitting structure composed of at least two beam splitting devices, the reflected light generated by the multiple linear light spots is spatially split so that the multiple reflected light beams are guided to the corresponding linear array scanning imaging devices for imaging and acquisition. The method of simultaneously imaging and acquiring multiple linear light spots using multiple linear array scanning imaging devices to obtain multiple scanned images of the target wafer includes: The position information of the target wafer during its movement is acquired, and the position information is synchronously sent to the multiple linear array scanning imaging devices; Using the multiple linear array scanning imaging devices, the reflection images corresponding to the multiple linear light spots are acquired synchronously according to the position information to obtain the multiple scan images. The multiple scan images are multiple spatiotemporally aligned images corresponding to the reflection responses of the same area and different illumination channels on the target wafer.

7. The system according to claim 6, characterized in that, The system also includes at least one beam splitter; The at least one beam splitter is used to spatially split the reflected light generated by the plurality of linear light spots, so as to guide the multiple reflected light beams to the corresponding linear array scanning imaging devices for imaging and acquisition.

8. A computer program product, characterized in that, When the instructions in the computer program product are executed by the processor of the electronic device, the electronic device performs the wafer scanning image acquisition method as described in any one of claims 1-5.

Images