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CN-121998835-A - Real-time image enhancement method and system based on CD-SEM raster scanning segmentation

CN121998835ACN 121998835 ACN121998835 ACN 121998835ACN-121998835-A

Abstract

The invention discloses a real-time image enhancement method and a system based on CD-SEM raster scanning segmentation, wherein the method comprises the following steps of S1, based on the preset size of an image processing block and overlapping area parameters, controlling an electron beam of a CD-SEM to scan an area to be detected according to a raster scanning path to obtain an image acquisition block, S2, acquiring the image acquisition block, sequentially performing local histogram statistics, clipping and equalization processing on the current image acquisition block to generate and output a corresponding enhanced image processing block, S3, splicing the current image processing block and a spliced image, directly splicing pixels which are non-overlapped between the current image processing block and adjacent spliced image processing blocks, and carrying out gray fusion on the pixels of the overlapping area by adopting a weighted average algorithm to generate a final integral enhanced image. The invention has the advantages of high efficiency, low delay, low memory occupation, seamless integration, excellent enhancement effect and the like.

Inventors

  • TANG SHAOJIE
  • ZHOU WENJIAN
  • CHEN QINGGUANG
  • FAN JIANGHUA
  • CHEN LONG

Assignees

  • 中国电子科技集团公司第四十八研究所

Dates

Publication Date
20260508
Application Date
20260127

Claims (10)

  1. 1. A method for real-time image enhancement based on CD-SEM raster scan segmentation, comprising the steps of: S1, based on the preset size of an image processing block and the parameters of an overlapping area, controlling an electron beam of a CD-SEM to scan an area to be detected according to a raster scanning path to obtain an image acquisition block, wherein the scanning path enables the adjacent scanning physical blocks to have the overlapping area in the horizontal direction and/or the vertical direction; S2, acquiring an image acquisition block output in the step S1, sequentially performing local histogram statistics, clipping and equalization on the current image acquisition block, generating a corresponding enhanced image processing block and outputting the corresponding enhanced image processing block; s3, receiving the enhanced image processing block output in the step S2 in real time, and splicing the current image processing block and the spliced image, wherein non-overlapped pixels exist between the current image processing block and the adjacent spliced image processing block, splicing is directly performed, and gray fusion is performed on pixels in an overlapped area by adopting a weighted average algorithm, so that a final overall enhanced image is generated.
  2. 2. The method for real-time image enhancement based on CD-SEM raster scan segmentation according to claim 1, wherein in step S2, the specific procedure of cropping is: setting a clipping limit CL for each local histogram; Traversing each gray level of the local histogram, and cutting off the exceeding part if the pixel number of the gray level exceeds the cutting limit CL; The total number of clipped pixels is evenly redistributed to all gray levels, resulting in a clipped and redistributed histogram.
  3. 3. The CD-SEM raster scan segmentation based real-time image enhancement method of claim 2, wherein the clipping CL is calculated as: Wherein the method comprises the steps of Is an adjustable parameter.
  4. 4. A real-time image enhancement method based on CD-SEM raster scan segmentation according to claim 1 or 2 or 3, wherein in step S2, the specific procedure of the equalization process is: Calculating a cumulative distribution function CDF based on the histogram obtained after clipping; And constructing a mapping function according to the accumulated distribution function CDF to obtain a new gray value.
  5. 5. The method for CD-SEM raster scan segmentation based real-time image enhancement according to claim 4, wherein the mapping function The formula of (2) is: as a mapping function, a new gray value after the gray value k is mapped; N is the total number of pixels of the image block, L is the maximum gray level number; Is the cumulative distribution function value for the ash value k.
  6. 6. A method of real-time image enhancement based on CD-SEM raster scan segmentation according to claim 1 or 2 or 3, characterized in that in step S3 the weighted average algorithm is specifically: for any pixel point A in the overlapping area, the gray value of the image block on the left side or the upper side after the image block is equalized is The gray value of the image block on the right side or the lower side after equalization is New gray value after the pixel is fused The method comprises the following steps: Wherein the method comprises the steps of For the center distance of the pixel point a from the left or upper image block, The pixel point A is at a distance from the center of the image block on the right side or the lower side.
  7. 7. A method of real-time image enhancement based on CD-SEM raster scan segmentation according to claim 1 or 2 or 3, wherein in step S1 the steps of the scan path are aligned or in integer multiples with the size of the preset image processing block.
  8. 8. A computer program product comprising a computer program which, when run by a processor, performs the steps of the method according to any one of claims 1-7.
  9. 9. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, performs the steps of the method according to any of claims 1-7.
  10. 10. A real-time image enhancement system based on CD-SEM raster scan segmentation, comprising a memory and a processor connected to each other, said memory having stored thereon a computer program, characterized in that said computer program, when being executed by the processor, performs the steps of the method according to any of claims 1-7.

Description

Real-time image enhancement method and system based on CD-SEM raster scanning segmentation Technical Field The invention mainly relates to the technical field of semiconductors, in particular to a real-time image enhancement method and system based on CD-SEM raster scanning segmentation. Background In semiconductor manufacturing processes, critical dimension scanning electron microscopy (CD-SEM) is a core device for chip linewidth measurement, defect detection, and topography analysis. CD-SEM generates a gray scale image by raster scanning a focused electron beam over the sample surface and collecting secondary or backscattered electron signals. However, due to factors such as sample material, charge effect, electron beam noise, etc., the obtained original image often has problems of low overall contrast and blurred details, which seriously affect the accuracy of subsequent automatic measurement and defect identification. The traditional image enhancement scheme is a contrast limited adaptive histogram equalization algorithm (CLAHE), which is used for independently carrying out histogram equalization on each small block by dividing the image into a plurality of small blocks, and limiting the excessive enhancement of local contrast so as to improve the overall contrast of the image and simultaneously highlight local details. However, the conventional CLAHE algorithm is directed to processing digital images that have been fully acquired. When faced with the high resolution produced by CD-SEM (e.g., 40964096 Pixels or higher) image, directly applying the CLAHE algorithm brings about two main problems: 1. and the huge memory cost is that the whole high-resolution image is required to be loaded into a memory and subjected to blocking processing, and the requirement on computer hardware is high. 2. Processing delay, namely, processing can be started after the whole image is scanned and transmitted, and the requirement of real-time performance in online detection cannot be met. The CD-SEM itself works by raster scanning line by line and block by block. The prior art regards image acquisition and image enhancement as two independent, serial stages, which are inefficient and take up significant memory. Disclosure of Invention Aiming at the technical problems existing in the prior art, the invention provides a CD-SEM raster scanning blocking-based real-time image enhancement method and system with high efficiency and low memory occupation. In order to solve the technical problems, the technical scheme provided by the invention is as follows: a real-time image enhancement method based on CD-SEM raster scan segmentation, comprising the steps of: S1, based on the preset size of an image processing block and the parameters of an overlapping area, controlling an electron beam of a CD-SEM to scan an area to be detected according to a raster scanning path to obtain an image acquisition block, wherein the scanning path enables the adjacent scanning physical blocks to have the overlapping area in the horizontal direction and/or the vertical direction; S2, acquiring an image acquisition block output in the step S1, sequentially performing local histogram statistics, clipping and equalization on the current image acquisition block, generating a corresponding enhanced image processing block and outputting the corresponding enhanced image processing block; s3, receiving the enhanced image processing block output in the step S2 in real time, and splicing the current image processing block and the spliced image, wherein non-overlapped pixels exist between the current image processing block and the adjacent spliced image processing block, splicing is directly performed, and gray fusion is performed on pixels in an overlapped area by adopting a weighted average algorithm, so that a final overall enhanced image is generated. Preferably, in step S2, the specific process of clipping is: setting a clipping limit CL for each local histogram; Traversing each gray level of the local histogram, and cutting off the exceeding part if the pixel number of the gray level exceeds the cutting limit CL; The total number of clipped pixels is evenly redistributed to all gray levels, resulting in a clipped and redistributed histogram. Preferably, the calculation formula of clipping CL is: Wherein the method comprises the steps of Is an adjustable parameter. Preferably, in step S2, the specific procedure of the equalization process is: Calculating a cumulative distribution function CDF based on the histogram obtained after clipping; And constructing a mapping function according to the accumulated distribution function CDF to obtain a new gray value. Preferably, the mapping functionThe formula of (2) is: as a mapping function, a new gray value after the gray value k is mapped; N is the total number of pixels of the image block, L is the maximum gray level number; Is the cumulative distribution function value for the ash value k. Preferably, in step S3,