Wafer image processing method and device and wafer scanning system

Abstract

The embodiment of the application discloses a wafer image processing method, device and wafer scanning system, the method comprises the following steps: under the condition that a target wafer is illuminated based on a light source, a camera is controlled to perform multiple batch scans on the target wafer in a line scanning mode. Each batch scan comprises scanning one or more rows of pixels in a line scanning mode to obtain an original scan image of the batch scan. The original scan image of the batch scan comprises the image of the one or more rows of pixels of the batch scan. The light power measurement device is used to obtain the corresponding light emitting power of each batch scan. The corresponding light emitting power of each batch scan is the light emitting power of the light source during each batch scan. The brightness value of the pixel in the original scan image of each batch scan is adjusted according to the reference pixel brightness value and the light emitting power during each batch scan to obtain a pixel correction image corresponding to the batch scan. The target scan image of the target wafer is obtained according to the multiple pixel correction images of the multiple batch scans.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, and particularly relates to a wafer image processing method and device and a wafer scanning system. BACKGROUND

[0002] In the field of wafer defect detection, a light source is needed to generate a beam of illumination light to irradiate the wafer surface, and then a time delay integration camera is used to scan the image of the wafer surface to identify defects. During the scanning process, the camera remains stationary, and the camera scans only one row of pixels each time, and the scanning of the entire wafer surface is completed by moving the wafer. However, as the process size of semiconductor becomes smaller and smaller, the wafer surface image scanned by the camera will become weaker and weaker, that is, more and more sensitive to noise. At the same time, the light power of the light source generating the illumination will fluctuate constantly, resulting in that the wafer surface image scanned by the camera will superimpose additional noise, the wafer surface image acquisition effect is poor, and thus the wafer defect detection is missed and false detection occurs. SUMMARY

[0003] The present application provides a wafer image processing method, device and wafer scanning system, which can eliminate the pixel noise in the original scanning image due to the fluctuation of the light power of the light source, and improve the wafer surface image scanning effect.

[0004] In a first aspect, the present application provides a wafer image processing method, wherein the method comprises: in the case that a target wafer is illuminated based on a light source, controlling a camera to perform multiple batch scans on the target wafer in a row scanning manner; wherein each batch scan comprises scanning one or more rows of pixels in a row scanning manner to obtain an original scanning image of the batch scan, and the original scanning image of the batch scan comprises the image of the one or more rows of pixels of the batch scan; obtaining the light emitting power corresponding to each batch scan by a light power measuring device, wherein the light emitting power corresponding to each batch scan is the light emitting power of the light source at each batch scan; adjusting the brightness value of each pixel in the original scanning image of each batch scan according to the reference pixel brightness value and the light emitting power at each batch scan to obtain a pixel correction image corresponding to the batch scan; and obtaining a target scanning image of the target wafer according to the multiple pixel correction images obtained by the multiple batch scans.

[0005] In the present application, during the scanning of the camera on the target wafer, the brightness value of each pixel in the original scanning image is adjusted by combining the reference pixel brightness value with the light emitting power at each batch scan, that is, the pixel value of the original scanning image obtained under different light emitting powers is compensated for gain, and the pixel noise in the original scanning image due to the fluctuation of the light power of the light source is eliminated.

[0006] In a possible implementation, the method further includes: when the original scan image of each batch scan is an image of one row of pixels, adjusting the brightness value of the one row of pixels in the original scan image of each batch scan according to the reference pixel brightness value and the corresponding light emitting power of each batch scan; and when the original scan image of each batch scan is an image of multiple rows of pixels, adjusting the brightness value of the multiple rows of pixels in the original scan image of each batch scan according to the reference pixel brightness value and the corresponding light emitting power of each batch scan. Since the light emitting power of the light source fluctuates little in a short time, the efficiency of light emitting power detection can be improved by obtaining the light emitting power of the light source once after the camera scans the target wafer multiple times to serve as the corresponding light emitting power of each batch scan.

[0007] In a possible implementation, the reference pixel brightness value is obtained by the following method: before the camera is controlled to perform multiple batch scans on the target wafer in a row scanning manner based on the light source illuminating the target wafer, the light emitting power of the light source is adjusted multiple times based on the light source illuminating the reference wafer, and after the light emitting power of the light source is adjusted each time, the camera is controlled to scan the reference wafer to obtain a reference wafer image; multiple reference wafer images obtained by scanning the reference wafer after the light emitting power of the light source is adjusted multiple times are acquired, and the reference pixel brightness value is obtained according to the multiple target light emitting powers corresponding to the multiple times of adjusting the light emitting power of the light source and the multiple reference wafer images. The brightness value of each pixel in the original scan image is adjusted by combining the reference pixel brightness value with the light emitting power at each batch scan, that is, the pixel value of the original scan image obtained under different light emitting powers is compensated for gain, so that the pixel noise in the original scan image caused by fluctuation of the light emitting power of the light source is eliminated.

[0008] In a possible implementation, the reference pixel brightness value is obtained according to the multiple target light emitting powers corresponding to the multiple times of adjusting the light emitting power of the light source and the multiple reference wafer images, including: obtaining a brightness balance value corresponding to each target light emitting power based on the brightness value of the pixel contained in the reference wafer image corresponding to each target light emitting power in the multiple target light emitting powers, to obtain multiple brightness balance values corresponding to the multiple target light emitting powers; sampling the light emitting power of the light source after the light emitting power of the light source is adjusted multiple times to obtain multiple sampling light emitting powers, and obtaining a light emitting power balance value according to the multiple sampling light emitting powers; and determining the brightness balance value corresponding to the target light emitting power equal to the light emitting power balance value in the multiple target light emitting powers as the reference pixel brightness value. The light emitting power balance value is obtained according to the multiple sampling light emitting powers, and the reference pixel brightness value is selected based on the light emitting power balance value, so that the interference caused by fluctuation of the light emitting power of the light source is reduced.

[0009] In a possible implementation, the adjusting of the brightness value of each pixel in the original scan image of each batch scan to obtain the pixel correction image corresponding to the batch scan according to the reference pixel brightness value and the light emitting power at each batch scan comprises: taking a brightness equalization value corresponding to a target light emitting power equal to the light emitting power corresponding to each batch scan as a target brightness equalization value; and multiplying the brightness value of each pixel in the original scan image by a correction coefficient corresponding to the original scan image to obtain the pixel correction image, wherein the correction coefficient corresponding to the original scan image is a ratio of the reference pixel brightness value to the target brightness equalization value.

[0010] In a possible implementation, the method further comprises: controlling the trigger pulse generator to send a first trigger pulse and a second trigger pulse to the camera and the light power measuring device respectively, so as to control the camera to scan one row of pixels of the target wafer under each first trigger pulse, and control the light power measuring device to obtain the light emitting power of the light source once under each second trigger pulse; and the frequency of the first trigger pulse sent by the trigger pulse generator to the camera is greater than or equal to the frequency of the second trigger pulse sent to the light power measuring device.

[0011] In a second aspect, the present application provides a wafer image processing device, which comprises: an image acquisition module, configured to control a camera to perform batch scanning on a target wafer in a row scanning manner based on illumination of the target wafer by a light source; wherein each batch scan comprises scanning one or more rows of pixels in a row scanning manner to obtain an original scan image of the batch scan, and the original scan image of the batch scan comprises images of the one or more rows of pixels of the batch scan; an image processing module, configured to obtain light emitting power of the light source corresponding to each batch scan by a light power measuring device; the image processing module is configured to adjust brightness values of pixels in the original scan image of each batch scan according to a reference pixel brightness value and the light emitting power at each batch scan to obtain a pixel correction image corresponding to the batch scan; and the image processing module is configured to obtain a target scan image of the target wafer according to a plurality of pixel correction images obtained through a plurality of batch scans.

[0012] In the present application, during the scanning of the target wafer by the camera, the brightness value of each pixel in the original scan image is adjusted by combining the reference pixel brightness value with the light emitting power at each batch scan, that is, the pixel value of the original scan image obtained under different light emitting powers is compensated for gain, so as to eliminate pixel noise in the original scan image due to fluctuation of the light power of the light source.

[0013] In a possible implementation, the image processing module is configured to adjust the brightness value of a row of pixels in the original scan image according to the reference pixel brightness value and the corresponding light emitting power of each batch scan; or adjust the brightness value of multiple rows of pixels in the original scan image according to the reference pixel brightness value and the corresponding light emitting power of each batch scan. Since the light emitting power of the light source fluctuates little in a short time, the efficiency of light emitting power detection can be improved by obtaining the light emitting power of the light source once after multiple scans of the target wafer by the camera, as the corresponding light emitting power of each batch scan.

[0014] In a possible implementation, before the camera performs multiple batch scans on the target wafer in a row scanning manner based on the light source, the image acquisition module is further configured to, in a case of illuminating the reference wafer based on the light source, adjust the light emitting power of the light source multiple times, and control the camera to scan the reference wafer to obtain a reference wafer image after each adjustment of the light emitting power of the light source; and the image processing module is further configured to obtain multiple reference wafer images obtained by scanning the reference wafer after the light emitting power of the light source is adjusted multiple times, and obtain the reference pixel brightness value according to the multiple target light emitting powers corresponding to the multiple adjustments of the light emitting power of the light source and the multiple reference wafer images. The brightness value of each pixel in the original scan image is adjusted by combining the reference pixel brightness value with the light emitting power at each batch scan, that is, the pixel value of the original scan image obtained under different light emitting powers is compensated for gain, so that the pixel noise in the original scan image caused by fluctuation of the light power of the light source is eliminated.

[0015] In a third aspect, the present application provides a wafer scanning system. The target wafer scanning system includes a stage, a camera, a light source, a light power measuring device, and a controller. The light source is configured to provide illumination light to a wafer on the stage. The controller is configured to obtain a target scan image of the target wafer according to the method provided in the first aspect.

[0016] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program. The computer program is adapted to be loaded by a processor and execute the wafer image processing method provided in the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a schematic diagram of an architecture of a wafer scanning system provided by an embodiment of the present application;

[0018] Figure 2 FIG. 4 is a schematic diagram of light emitting power detection of a light source provided by an embodiment of the present application;

[0019] Figure 3 FIG. 6 is a flowchart of a wafer image processing method provided by an embodiment of the present application;

[0020] Figure 4 is a structural schematic diagram of a wafer image processing device provided by an embodiment of the present application;

[0021] Figure 5 is another structural schematic diagram of a wafer image processing device provided by an embodiment of the present application.

[0022] Legend of reference signs:

[0023] 10: stage;

[0024] 11: wafer;

[0025] 20: camera;

[0026] 30: light source;

[0027] 40: controller;

[0028] 50: optical power measuring device;

[0029] 60: beam splitter;

[0030] 70: wafer image processing device;

[0031] 71: image acquisition module;

[0032] 72: image processing module;

[0033] 721: pixel correction module;

[0034] 7211: pixel buffer;

[0035] 7212: pixel calculation;

[0036] 7213: second synchronization interface;

[0037] 722: synchronization module;

[0038] 7221: trigger pulse generator;

[0039] 7222: stage interface;

[0040] 7223: light emitting power interface;

[0041] 7224: correction coefficient mapping table;

[0042] 7225: host computer interface;

[0043] 7226: first synchronization interface;

[0044] 80: host computer. DETAILED DESCRIPTION

[0045] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0046] Please refer to Figure 1 , Figure 1 is a schematic diagram of an architecture of a wafer scanning system provided by the embodiments of the present application. As shown in Figure 1 , the wafer scanning system can include a stage 10, a camera 20 and a light source 30. The stage 10 can be used to load a wafer 11 and adjust the wafer position by movement. Specifically, the wafer loaded on the stage 10 can be a target wafer, the light source 30 is used to provide illumination light to the target wafer on the stage 10, and the camera 20 is used to scan the target wafer to obtain a scanning image of the target wafer based on the illumination of the target wafer by the light source 30, and perform defect detection on the target wafer based on the obtained scanning image, and the camera 20 can be a time delay integration camera 20 or other device with wafer image acquisition function. In the working process of the wafer scanning system, the camera 20 remains stationary, and the camera 20 can only scan one row of pixels at a time, and the horizontal and vertical movement of the stage 10 drives the target wafer to move to complete the scanning of the entire surface of the target wafer. However, as the semiconductor process technology size becomes smaller and smaller, the wafer surface image scanned by the camera 20 will become weaker and weaker, that is, more and more sensitive to noise. At the same time, the light power of the light source 30 will also fluctuate constantly when the camera 20 scans, resulting in that the wafer surface image scanned by the camera 20 will superimpose additional noise, the wafer surface image acquisition effect is poor, and thus the wafer defect detection is missed and false detection occurs.

[0047] The wafer image processing method provided by the embodiments of the present application can be applied to the wafer scanning system. Specifically, the wafer scanning system can further include a controller 40 and a light power measuring device 50, the light power measuring device 50 is used to obtain the light emitting power of the light source 30 when illuminating the wafer, and the light power measuring device 50 can be a photodiode or the like. Again refer to Figure 1 , Figure 1In the wafer scanning system shown, the controller 40 controls the camera 20 to perform multiple batch scans on the target wafer in a line scanning manner based on the illumination of the target wafer by the light source 30, wherein each batch scan includes scanning one or more rows of pixels in a line scanning manner to obtain a raw scan image of the batch scan, and the raw scan image of the batch scan includes the image of the one or more rows of pixels of the batch scan. At the same time, the controller 40 controls the light power measuring device 50 to receive the light emitted by the light source 30 through the beam splitter 60 during the scanning of the target wafer by the camera 20, so as to obtain the light emitting power of the light source 30 at each batch scan. Then, the controller 40 can obtain the raw scan image from the camera 20 and the light emitting power of the light source 50 at each batch scan, and adjust the brightness value of each pixel in the raw scan image according to the reference pixel brightness value and the light emitting power corresponding to each batch scan to obtain a pixel correction image, and output the pixel correction image as the target scan image of the target wafer. Here, during the scanning of the target wafer by the camera 20, the brightness value of each pixel in the raw scan image of each batch scan is adjusted according to the reference pixel brightness value and the light emitting power corresponding to each batch scan to obtain a pixel correction image corresponding to the batch scan, and the target scan image of the target wafer is obtained according to the multiple pixel correction images obtained by multiple batch scans. Here, by compensating the pixel value of the raw scan image obtained under different light emitting powers, the pixel noise in the raw scan image caused by the fluctuation of the light power of the light source 30 is eliminated, and the wafer surface image scanning effect is improved.

[0048] In some possible embodiments, during the scanning of the target wafer by the camera, when the raw scan image of each batch scan is the image of one row of pixels, the brightness value of the one row of pixels in the raw scan image is adjusted according to the reference pixel brightness value and the light emitting power corresponding to each batch scan. When the raw scan image of each batch scan is the image of multiple rows of pixels, the brightness value of the multiple rows of pixels in the raw scan image is adjusted according to the reference pixel brightness value and the light emitting power corresponding to each batch scan. Taking the raw scan image of each batch scan as the image of multiple rows of pixels as an example, the frequency of the scanning of the wafer by the controller is greater than the frequency of the obtaining of the light emitting power of the light source by the light power measuring device. Referring to Figure 2 , Figure 2 is a schematic diagram of the detection of the light emitting power of the light source provided by the embodiments of the present application. As Figure 2As shown, in the process of scanning the target wafer by the camera, each batch scanning includes scanning N rows of pixels in a line scanning manner, that is, the camera scans the target wafer N times in each batch scanning to obtain the original scanning image of the batch scanning. The corresponding light emitting power of each batch scanning can be the light emitting power of the light source obtained when the first scanning in the batch scanning is performed. For example, the camera is controlled to scan the target wafer N times in a line scanning manner from t1 to t2 to obtain the original scanning image of the batch scanning, and the original scanning image includes the images of N rows of pixels of the batch scanning. At t1 when the first scanning is performed, the light power measuring device is controlled to obtain the light emitting power P1 of the light source, and P1 is taken as the corresponding light emitting power of the batch scanning. It can be understood that the corresponding light emitting power of each batch scanning can also be the light emitting power of the light source obtained when the second to Nth scanning in the batch scanning is performed, and the specific value can be determined according to the actual application scene, which is not limited here. The controller can adjust the brightness value of each pixel in the original scanning image obtained N times after t1 and before t2 according to the reference pixel brightness value and the corresponding light emitting power P1 of the batch scanning. Further, at t2, the light power measuring device is controlled to obtain the light emitting power P2 of the light source, which can be taken as the corresponding light emitting power of the next batch scanning, and the brightness value of each pixel in the original scanning image obtained N times after t2 is adjusted according to the reference pixel brightness value and the corresponding light emitting power P2 of the next batch scanning.

[0049] In some possible embodiments, the reference pixel brightness value is obtained by the following method: before the camera is controlled to perform multiple batch scans on the target wafer in a line scanning manner based on the light source illuminating the target wafer, the controller can also control the light source to adjust the light emitting power multiple times based on the light source illuminating the reference wafer, and after each adjustment of the light emitting power of the light source, control the camera to perform a scan on the reference wafer to obtain a reference wafer image. The controller can obtain a reference wafer image of the reference wafer after each adjustment of the light emitting power of the light source to obtain multiple reference wafer images, and obtain the reference pixel brightness value according to the multiple target light emitting powers corresponding to the multiple adjustments of the light emitting power of the light source and the multiple reference wafer images. Specifically, the controller obtains a brightness balance value corresponding to each target light emitting power based on the brightness values of the pixels contained in the reference wafer image corresponding to each target light emitting power, to obtain multiple brightness balance values corresponding to the multiple target light emitting powers. For example, the controller can start from 0 of the light emitting power of the light source based on the light source illuminating the reference wafer, and each time the light emitting power of the light source is increased by 1%*Pm until the light emitting power of the light source is Pm, and after each time the light emitting power of the light source is increased by 1%*Pm, the camera is controlled to perform a scan on the reference wafer to obtain a reference wafer image, and Pm can be the maximum light emitting power of the light source. The controller obtains a brightness balance value corresponding to each target light emitting power based on the brightness values of the pixels contained in the reference wafer image corresponding to 1%*Pm, 2%*Pm, …, Pm of the target light emitting power, for example, obtains the average values GL1, GL2, …, GL100 of the brightness values of the pixels contained in the reference wafer images corresponding to 1%*Pm, 2%*Pm, …, Pm of the target light emitting power, respectively, as the brightness balance values corresponding to each target light emitting power. Then, after the controller adjusts the light emitting power of the light source multiple times, the controller controls the light power measuring device to sample the light emitting power of the light source to obtain multiple sampling light emitting powers, and the controller obtains the light emitting power balance value according to the multiple sampling light emitting powers. For example, after the controller controls the light emitting power of the light source to be Pm, the controller controls the light power measuring device to detect the light emitting power of the light source at a detection frequency of no less than 10 kHz to obtain multiple sampling light emitting powers, such as at least 2500 sampling light emitting powers. The controller can obtain the light emitting power balance value based on the average of the multiple sampling light emitting powers, and determine the brightness balance value corresponding to the target light emitting power equal to the light emitting power balance value in the multiple target light emitting powers as the reference pixel brightness value. For example, the controller obtains the light emitting power balance value as 88%*Pm based on the average of the multiple sampling light emitting powers, and determines the brightness balance value GL88 corresponding to the target light emitting power of 88%*Pm as the reference pixel brightness value.The luminance value of each pixel in the original scan image is adjusted according to the reference pixel luminance value and the luminous power in each batch scan, i.e. the pixel value of the original scan image obtained under different luminous power is compensated by gain, so as to eliminate the pixel noise in the original scan image caused by the luminous power fluctuation of the light source.

[0050] In some possible embodiments, in the process of adjusting the luminance value of each pixel in the original scan image of each batch scan according to the reference pixel luminance value and the luminous power in each batch scan to obtain the pixel correction image corresponding to the current batch scan, one of the multiple target luminous powers equal to the luminous power in each batch scan can be taken as the target luminance balance value. Then, the luminance value of each pixel in the original scan image is multiplied by the correction coefficient corresponding to the original scan image to obtain the pixel correction image, wherein the correction coefficient corresponding to the original scan image is the ratio of the reference pixel luminance value to the target luminance balance value. For example, if the luminance balance values corresponding to the multiple target luminous powers 1%*Pm, 2%*Pm, …, Pm are GL1, GL2, …, GL100 respectively, when the controller obtains the original scan image of the current batch scan and the luminous power Px corresponding to the current batch scan, the target luminous power equal to the luminous power Px corresponding to the current batch scan is matched from the multiple target luminous powers. For example, if the controller obtains the luminous power Px corresponding to the current batch scan equal to 60%Pm, and the reference pixel luminance value is GL88, the luminance balance value GL60 corresponding to the target luminous power 60%*Pm is taken as the target luminance balance value, and the original scan image is multiplied by the correction coefficient corresponding thereto, i.e. GL88 / GL60, so as to obtain the pixel correction image corresponding to the current batch scan.

[0051] It can be understood that, after the camera performs multiple batch scans on the target wafer in the form of row scanning to obtain the original scan images of the multiple batch scans, the original scan images can include the images of one or more rows of pixels in each batch scan, and each row or multiple rows of pixels in each original scan image can correspond to a pixel row number, and the controller can obtain the correction coefficient corresponding to each original scan image based on the pixel row number corresponding to each original scan image, so as to adjust the luminance value of each pixel in the original scan image according to the corresponding correction coefficient, so as to obtain the pixel correction image corresponding to each batch scan. Finally, the target scan image of the target wafer is obtained according to the multiple pixel correction images obtained by the multiple batch scans and is output.

[0052] Referring to Figure 3 , Figure 3 is a flowchart of a wafer image processing method provided by an embodiment of the present application. Figure 2The wafer image processing method shown is applicable to Figure 1 or Figure 2 The wafer scanning system of each corresponding embodiment, such as Figure 3 As shown, the wafer image processing method provided by the present application can include the following steps:

[0053] Step S101, in the case of illuminating the target wafer based on the light source, the camera is controlled to perform multiple batch scans on the target wafer in a line scanning manner.

[0054] Step S102, the light power measurement device is used to obtain the light emitting power corresponding to each batch scan, and the luminance value of each pixel in the original scan image of each batch scan is adjusted according to the reference pixel luminance value and the light emitting power at the time of each batch scan to obtain a pixel correction image corresponding to the present batch scan.

[0055] In some possible embodiments, in the case of illuminating the target wafer based on the light source, the camera is controlled to perform multiple batch scans on the target wafer in a line scanning manner. Each batch scan includes scanning one or more rows of pixels in a line scanning manner to obtain an original scan image of the present batch scan, and the original scan image of the present batch scan includes the image of one or more rows of pixels of the present batch scan. At the same time, the controller controls the light power measurement device to receive light emitted from the light source through the beam splitter during the scanning of the target wafer by the camera, so as to obtain the light emitting power of the light source at each batch scan.

[0056] In some possible embodiments, during the scanning of the target wafer by the camera, when the original scan image of each batch scan is the image of one row of pixels, the luminance value of the one row of pixels in the original scan image is adjusted according to the reference pixel luminance value and the light emitting power corresponding to each batch scan. When the original scan image of each batch scan is the image of multiple rows of pixels, the luminance value of the multiple rows of pixels in the original scan image is adjusted according to the reference pixel luminance value and the light emitting power corresponding to each batch scan. Taking the case that the original scan image of each batch scan is the image of multiple rows of pixels as an example, the frequency of the camera scanning the wafer controlled by the controller is greater than the frequency of the light power measurement device obtaining the light emitting power of the light source, and the specific process of obtaining the light emitting power of the light source can be referred to the description of the above Figure 2 .

[0057] In some possible embodiments, before the camera is controlled to perform multiple batch scans on the target wafer in a row scanning manner, the light source can be adjusted multiple times in a manner that the light source illuminates the reference wafer based on the light source, and the camera is controlled to perform a scan on the reference wafer to obtain a reference wafer image after each adjustment of the light source. A reference wafer image of the reference wafer after each adjustment of the light source can be obtained to obtain multiple reference wafer images, and reference pixel brightness values can be obtained according to multiple target light powers corresponding to the multiple adjustments of the light source and the multiple reference wafer images. Before the brightness values of the pixels in the original scan image are adjusted to obtain the pixel correction image, the light source can be adjusted multiple times in a manner that the light source illuminates the reference wafer based on the light source, and the camera is controlled to perform a scan on the reference wafer to obtain a reference wafer image after each adjustment of the light source. A reference wafer image of the reference wafer after each adjustment of the light source can be obtained to obtain multiple reference wafer images, and reference pixel brightness values can be obtained according to multiple target light powers corresponding to the multiple adjustments of the light source and the multiple reference wafer images. Specifically, the brightness balance value corresponding to each target light power can be obtained based on the brightness values of the pixels in the reference wafer image corresponding to each target light power, to obtain multiple brightness balance values corresponding to the multiple target light powers. For example, the light source can be adjusted in a manner that the light source illuminates the reference wafer based on the light source, starting from 0 of the light power of the light source, and increasing the light power of the light source by 1%*Pm each time until the light power of the light source is Pm, where Pm can be the maximum light power of the light source. The brightness balance value corresponding to each target light power can be obtained based on the brightness values of the pixels in the reference wafer image corresponding to 1%*Pm, 2%*Pm, …, Pm of the target light power, for example, the average values GL1, GL2, …, GL100 of the brightness values of the pixels in the reference wafer images corresponding to 1%*Pm, 2%*Pm, …, Pm of the target light power are obtained as the brightness balance values corresponding to the target light powers. Then, after the light power of the light source is adjusted multiple times, the light power of the light source is sampled by the light power measuring device to obtain multiple sampling light powers, and the light power balance value is obtained based on the multiple sampling light powers. For example, after the light power of the light source is controlled to be Pm, the light power of the light source is detected by the light power measuring device at a detection frequency of no less than 10 kHz to obtain multiple sampling light powers, for example, at least 2500 sampling light powers. The light power balance value can be obtained based on the average value of the multiple sampling light powers, and the brightness balance value corresponding to the target light power equal to the light power balance value in the multiple target light powers is determined as the reference pixel brightness value.For example, if the average of the above-mentioned multiple sampled luminous power values ​​yields a luminous power equalization value of 88%*Pm, then the luminous power equalization value GL88 corresponding to the target luminous power of 88%*Pm is determined as the reference pixel luminous value. By combining the reference pixel luminous value with the luminous power during each batch scan, the luminous value of each pixel in the original scanned image is adjusted. That is, the pixel values ​​of the original scanned image obtained under different luminous power are compensated for gain, eliminating pixel noise in the original scanned image caused by fluctuations in the light source power.

[0058] In some feasible implementations, during the process of adjusting the brightness values ​​of each pixel in the original scanned image of each batch scan to obtain the pixel-corrected image corresponding to this batch scan, based on the reference pixel brightness value and the luminous power during each batch scan, a brightness equalization value corresponding to the target luminous power that is equal to the luminous power during each batch scan can be used as the target brightness equalization value. Next, the brightness value of each pixel in the original scanned image is multiplied by the correction coefficient corresponding to the original scanned image to obtain the pixel-corrected image, where the correction coefficient corresponding to the original scanned image is the ratio of the reference pixel brightness value to the target brightness equalization value. For example, if the brightness equalization values ​​corresponding to multiple target luminous powers 1%*Pm, 2%*Pm, ..., Pm are GL1, GL2, ..., GL100 respectively, then after obtaining the original scanned image of this batch scan and the luminous power Px corresponding to this batch scan, a target luminous power equal to the luminous power Px corresponding to this batch scan is matched from the multiple target luminous powers. If the luminous power Px obtained in each batch scan is equal to 60% Pm, and the reference pixel brightness value is GL88, then the brightness equalization value GL60 corresponding to the target luminous power of 60%*Pm is taken as the target brightness equalization value. The original scanned image is multiplied by the corresponding correction coefficient, which is the ratio of the reference pixel brightness value to the target brightness equalization value GL60, i.e., multiplied by GL88 / GL60, so as to obtain the pixel correction image corresponding to this batch scan.

[0059] Step S103: Obtain the target scan image of the target wafer based on the multiple pixel correction images obtained from multiple batch scans.

[0060] In some feasible implementations, after the camera performs multiple batch scans of the target wafer in a row-scan manner to obtain multiple batch scan images, the original scan images may include one or more rows of pixels from each batch scan, and each row or multiple rows of pixels in the original scan image may correspond to a pixel row number. A correction coefficient corresponding to each original scan image can be obtained based on the pixel row number, and the brightness value of each pixel in the original scan image can be adjusted according to the corresponding correction coefficient to obtain a pixel-corrected image corresponding to each batch scan. Finally, the target scan image of the target wafer is obtained from the multiple pixel-corrected images obtained from the multiple batch scans and output.

[0061] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of a wafer image processing apparatus provided in an embodiment of this application. Figure 4 The wafer image processing apparatus 70 shown can be the one described above. Figure 1 The controller 40 has a computer program (including program code) that implements the above-described wafer image processing method. Alternatively, the above-described wafer image scanning device can also be a computer program, such as an application software. This device can be used to execute the corresponding steps in the wafer image processing method provided in the embodiments of this application. Figure 4 As shown, the wafer image processing apparatus 70 may include an image acquisition module 71 and an image processing module 72.

[0062] Image acquisition module 71 is used to control the camera to acquire the original scan image of the target wafer when the target wafer is illuminated by a light source;

[0063] The image processing module 72 is used to acquire the luminous power of each batch scan when the light source illuminates the target wafer, and adjust the brightness value of each pixel in the original scan image according to the reference pixel brightness value and the luminous power corresponding to each batch scan to obtain a pixel-corrected image.

[0064] Image processing module 72 is used to output a pixel-corrected image as a target scan image of the target wafer.

[0065] The specific functional implementation of the image acquisition module 71 can be found in the above description. Figure 3 The corresponding step S101 in the embodiment; the specific functional implementation of the image processing module 72 can be found in the above. Figure 3 Steps S102 and S103 in the corresponding embodiments will not be described in detail here.

[0066] In some feasible implementations, the image processing module 72 described above may include a pixel correction module 721 and a synchronization module 722. See also...Figure 5 , Figure 5 is another structure schematic diagram of the wafer image processing device 70 provided by the embodiment of the present application. As shown in the figure, Figure 5 the wafer image processing device 70 can include an image acquisition module 71 and an image processing module 72, and the image processing module 72 can include a pixel correction module 721 and a synchronization module 722. The synchronization module 722 is composed of a trigger pulse generator 7221, a stage interface 7222, a light emitting power interface 7223, a correction coefficient mapping table 7224, a host computer interface 7225, and a first synchronization interface 7226. The trigger pulse generator 7221 can be connected to the camera 20 through a coaxial cable, and the trigger pulse generator 7221 can output trigger pulses to the light power measuring device 50 and the camera 20 respectively, so that the synchronization module 722 can receive the sampling value from the light power measuring device 50, and the image acquisition module 71 can receive the scanning image from the camera 20. In addition, the synchronization module 722 receives the speed signal output by the stage 10 through the stage interface 7222, and outputs the trigger pulse to the T camera 20, so as to adjust the frequency of the trigger pulse output to the camera 20 in combination with the speed change of the motion stage. The correction coefficient mapping table 7224 can include a plurality of correction coefficients corresponding to a plurality of target light emitting powers, and the correction coefficient corresponding to each target light emitting power is the ratio of the reference pixel brightness value to the target light emitting power. The pixel correction module 721 is composed of a pixel buffer 7211, a pixel calculation 7212, and a second synchronization interface 7213. The pixel buffer 7211 is connected to the image acquisition module 71 and the pixel calculation 7212, and the image acquisition module 71 is connected to the camera 20 through an Ethernet port. In the online mode, the image acquisition module 71 receives the original scanning image (which can be a row of pixels) output by the camera 20, and does not immediately output to the host computer 80, but first sends to the pixel buffer 7211. At the same time, the synchronization module 722 receives the light emitting power at each batch scanning from the light power measuring device 50 through the light emitting power interface 7223, and compares the correction coefficient mapping table 7224 to output the correction coefficient corresponding to the target light emitting power equal to the light emitting power at each batch scanning to the second synchronization interface 7213 of the pixel correction module 721 through the first synchronization interface 7226. Then, the pixel calculation 7212 combines the original scanning image from the pixel buffer 7211 and the correction coefficient from the first synchronization interface 7226 to adjust the brightness value of each pixel in the original scanning image to obtain a pixel correction image, and finally output the pixel correction image to the host computer. It can be understood that the connection between the stage 10, the light power measuring device 50, the synchronization module 722, and the pixel correction module 721, etc. includes but is not limited to Ethernet port, serial port, etc. connection mode.

[0067] In addition, before adjusting the brightness value of each pixel in the original scanning image to obtain the pixel correction image, that is, in the measurement calibration mode, the synchronous module 722 can adjust the light emitting power of the light source multiple times based on the light source illuminating the reference wafer, and control the camera 20 to scan the reference wafer once to obtain a reference wafer image after each adjustment of the light emitting power of the light source. The image acquisition module 71 receives the reference wafer image output by the camera 20 and directly outputs to the upper computer. The reference pixel brightness value is obtained by the upper computer based on the multiple target light emitting powers obtained by adjusting the light emitting power of the light source multiple times and the multiple reference wafer images. The specific acquisition process can refer to the description above, and will not be described here.

[0068] In addition, the wafer image processing method provided in the embodiments of the present application also provides a computer readable storage medium, and the computer readable storage medium stores the computer program executed by the wafer image processing method mentioned above, and the computer program includes program instructions, and when the processor executes the program instructions, the wafer image processing method provided in the embodiments of the present application can be executed. Figures 1 to 5 The wafer image processing method provided in the embodiments of the present application, and the beneficial effects of using the same method will not be described here. For the technical details not disclosed in the computer readable storage medium embodiments of the present application, please refer to the description of the method embodiments of the present application. The computer readable storage medium can be the internal storage unit of the controller, such as the hard disk or the memory of the controller, which provides the wafer image processing method of each embodiment described above. The computer readable storage medium can also be an external storage device of the controller, such as the plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc. equipped on the controller. Further, the computer readable storage medium can include both the internal storage unit and the external storage device of the controller. The computer readable storage medium is used to store the computer program and other programs and data required by the controller. The computer readable storage medium can also be used to temporarily store the data that has been output or will be output.

[0069] Those skilled in the art can realize that the system and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been described in the above description. The professional can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

Claims

1. A wafer image processing method, characterized in that, The method includes: When illuminating a reference wafer with a light source, the luminous power of the light source is adjusted multiple times, and after each adjustment of the luminous power of the light source, the camera is controlled to scan the reference wafer to obtain a reference wafer image. Multiple reference wafer images are obtained by scanning the reference wafer after repeatedly adjusting the luminous power of the light source. Reference pixel brightness values ​​are obtained based on multiple target luminous powers corresponding to the multiple adjustments of the light source's luminous power and the multiple reference wafer images. A brightness equalization value corresponding to each target luminous power is obtained based on the brightness value of the pixels contained in the reference wafer image corresponding to each target luminous power, thus obtaining multiple brightness equalization values ​​corresponding to the multiple target luminous powers. After repeatedly adjusting the luminous power of the light source, the luminous power of the light source is sampled to obtain multiple sampled luminous powers. A luminous power equalization value is obtained based on the multiple sampled luminous powers. The brightness equalization value corresponding to the target luminous power that is equal to the luminous power equalization value among the multiple target luminous powers is determined as the reference pixel brightness value. When the target wafer is illuminated by the light source, the camera is controlled to perform multiple batch scans of the target wafer in a row-scanning manner; wherein, each batch scan includes scanning one or more rows of pixels in a row-scanning manner to obtain the original scan image of this batch scan, and the original scan image of this batch scan includes the image of one or more rows of pixels of this batch scan. The luminous power corresponding to each batch scan is obtained by an optical power measurement device, wherein the luminous power corresponding to each batch scan is the luminous power of the light source during each batch scan; The target brightness equalization value is taken as the brightness equalization value of the target luminous power that is equal to the luminous power corresponding to each batch scan among the plurality of target luminous powers. The brightness value of each pixel in the original scan image is multiplied by the correction coefficient corresponding to the original scan image to obtain the pixel correction image. The correction coefficient corresponding to the original scan image is the ratio of the reference pixel brightness value to the target brightness equalization value. The target scan image of the target wafer is obtained by correcting multiple pixels based on the multiple batch scans.

2. The method according to claim 1, characterized in that, The method further includes: When the original scanned image of each batch scan is an image of one row of pixels, the brightness value of one row of pixels in the original scanned image of each batch scan is adjusted according to the reference pixel brightness value and the luminous power corresponding to each batch scan. When the original scanned image of each batch scan is a multi-row pixel image, the brightness value of the multi-row pixels in the original scanned image of each batch scan is adjusted according to the reference pixel brightness value and the luminous power corresponding to each batch scan.

3. The method according to claim 1 or 2, characterized in that, The method further includes: The control trigger pulse generator sends a first trigger pulse and a second trigger pulse to the camera and the optical power measuring device, respectively, so as to control the camera to scan one row of pixels on the target wafer under each first trigger pulse, and control the optical power measuring device to acquire the luminous power of the light source once under each second trigger pulse; The frequency at which the trigger pulse generator sends the first trigger pulse to the camera is greater than or equal to the frequency at which it sends the second trigger pulse to the optical power measuring device.

4. A wafer image processing apparatus, characterized in that, include: The image acquisition module is used to adjust the luminous power of the light source multiple times when illuminating the reference wafer based on the light source, and after each adjustment of the luminous power of the light source, control the camera to scan the reference wafer to obtain a reference wafer image; An image processing module is configured to acquire multiple reference wafer images obtained by scanning the reference wafer after adjusting the luminous power of the light source multiple times, and to acquire reference pixel brightness values ​​based on multiple target luminous powers corresponding to the multiple adjustments of the luminous power of the light source and the multiple reference wafer images. Specifically, a brightness equalization value corresponding to each target luminous power is obtained based on the brightness value of the pixels contained in the reference wafer image corresponding to each target luminous power, thus obtaining multiple brightness equalization values ​​corresponding to the multiple target luminous powers. The module also samples the luminous power of the light source after multiple adjustments to obtain multiple sampled luminous powers, and obtains a luminous power equalization value based on the multiple sampled luminous powers. Finally, the module determines the brightness equalization value corresponding to the target luminous power that is equal to the luminous power equalization value among the multiple target luminous powers as the reference pixel brightness value. The image acquisition module is further configured to, when illuminating the target wafer based on the light source, control the camera to perform multiple batch scans of the target wafer in a row-scan manner; wherein each batch scan includes scanning one or more rows of pixels in a row-scan manner to obtain the original scan image of this batch scan, and the original scan image of this batch scan includes the image of one or more rows of pixels of this batch scan. The image processing module is used to obtain the luminous power corresponding to each batch scan through the optical power measurement device, wherein the luminous power corresponding to each batch scan is the luminous power of the light source during each batch scan; The image processing module is used to take a brightness equalization value corresponding to the target luminous power that is equal to the luminous power corresponding to each batch scan among the plurality of target luminous powers as the target brightness equalization value, and multiply the brightness value of each pixel in the original scan image by the correction coefficient corresponding to the original scan image to obtain a pixel correction image, wherein the correction coefficient corresponding to the original scan image is the ratio of the reference pixel brightness value to the target brightness equalization value. The image processing module is used to obtain the target scan image of the target wafer based on the multiple pixel correction images obtained from the multiple batch scans.

5. The wafer image processing apparatus according to claim 4, characterized in that, The image processing module is used to adjust the brightness value of a row of pixels in the original scanned image according to the reference pixel brightness value and the luminous power corresponding to each batch scan; Alternatively, the brightness values ​​of the multiple rows of pixels in the original scanned image can be adjusted based on the reference pixel brightness value and the luminous power corresponding to each batch scan.

6. A wafer scanning system, characterized in that, The wafer scanning system includes a stage, a camera, a light source, an optical power measurement device, and a controller; The light source is used to provide illumination light to the wafer on the stage; The controller is used to obtain a scanned image of the wafer according to any one of claims 1-3.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program adapted to be loaded by a processor and executed as described in any one of claims 1-3.

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