Electron Beam Inspection Reference Resizing for Pseudo Defect Filtering
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Solution Overview
Problem
Electron beam inspection systems face challenges in accurately distinguishing between genuine defects and pseudo defects, such as line-like or band-like patterns, which can lead to false defect identification due to charging effects, particularly in the inspection of ultrafine patterns on semiconductor wafers.
Innovation Solution
An electron beam inspection apparatus and method that includes image acquisition, resize processing, developed image generation, pseudo defect candidate pixel mapping, and comparison units to identify and correct pseudo defects by comparing secondary electron images with reference images, using design pattern data to differentiate between actual and pseudo defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electron beam inspection is performed on ultrafine patterns, then measurement precision is improved, but pseudo defects are generated due to charging effects
Solution Approach 1:
The patent applies preliminary action by performing resize processing on the figure pattern data before inspection to enlarge it in the electron beam scan direction. This preprocessing step creates a modified reference that accounts for charging effects, allowing the inspection system to distinguish between genuine defects and pseudo defects caused by charging. The resized pattern data is used to generate reference images that inherently compensate for the charging artifacts that would otherwise be misinterpreted as defects.
2Productivity
If electron beam scan direction is fixed, then inspection speed is maintained, but line-like pseudo patterns are generated along the scan direction
Solution Approach 1:
The patent applies parameter changes by modifying the figure pattern data through resize processing specifically in the electron beam scan direction. By enlarging the pattern dimensions along the scan direction, the system changes the geometric parameters of the reference pattern to match the distorted appearance caused by charging effects. This parameter modification allows the inspection to maintain fixed scan direction and speed while accurately recognizing and filtering out the line-like pseudo patterns that arise from charging.
3Measurement precision
If design pattern data is used directly for comparison, then inspection accuracy is high, but charging effects cause false defect identification
Solution Approach 1:
The patent applies copying by creating a modified copy of the design pattern data through resize processing. Instead of using the original design pattern data directly for comparison, the system generates a copied and enlarged version that reflects the expected appearance of patterns under electron beam inspection conditions including charging effects. This copied reference data is then used for comparison with actual inspection images, enabling the system to reliably distinguish between genuine defects and charging-induced artifacts.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the occurrence of pseudo defects in electron beam inspections, enhancing the accuracy of defect detection and preventing false defect identification, thereby improving the yield and reliability of semiconductor manufacturing.
Implementation Method 1
acquire a secondary electron image by scanning a substrate, on which a figure pattern is formed, with an electron beam, and detecting a secondary electron emitted due to irradiation with the electron beam
Data Source
AI summary
An electron beam inspection apparatus according to one aspect of the present invention includes an image acquisition mechanism to acquire a secondary electron image by scanning a substrate, on which a figure pattern is formed, with an electron beam, and detecting a secondary electron emitted due to irradiation with the electron beam by the scanning, a resize processing unit to perform, using design pattern data being a basis of the figure pattern, resize processing on the figure pattern to enlarge its size in a scan direction of the electron beam, a first developed image generation unit to generate, using the design pattern data which has not been resized, a first developed image by developing an image of a design pattern of a region corresponding to the secondary electron image, a second developed image generation unit to generate, using partial patterns enlarged by the resize processing in the figure pattern having been resized, a second developed image by developing an image of partial patterns in a region corresponding to the secondary electron image, a map generation unit to generate a pseudo defect candidate pixel map which can identify a pseudo defect candidate pixel that has no pattern in the first developed image and has a pattern in the second developed image, a reference image generation unit to generate a reference image of the region corresponding to the second electron image, and a comparison unit to compare, using the pseudo defect candidate pixel map, the second electron image with the reference image of the region corresponding to the second electron image.