Multibeam Inspection Image Blur Correction for Defect Detection
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Solution Overview
Problem
Multibeam inspection apparatuses using electron beams face challenges with image blur and distortion due to aberrations, leading to false defect identification, as different single beams have varying blur components depending on their distance from the objective lens, affecting the accuracy of defect detection.
Innovation Solution
The inspection method involves generating inspection images from multiple single beams, calculating their blur components, determining a reference blur component from the range with the largest number of images, and correcting images outside this range to match the reference, ensuring consistent blur levels across all images for accurate defect identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multibeam is used to irradiate the inspection target, then the inspection speed is improved, but the image blur and distortion increase due to different aberrations in each single beam
Solution Approach 1:
The patent calculates blur components for each inspection image based on the distance from the light axis and applies specific blur correction parameters to each image. This parameter-based correction approach allows the system to maintain high inspection speed while compensating for the varying aberrations in each beam, thereby resolving the contradiction between productivity and measurement precision.
2Area of stationary object
If single beams are positioned at different distances from the light axis, then the inspection coverage is improved, but the false defect identification increases due to varying blur components
Solution Approach 1:
The patent applies different blur correction processing to each inspection image based on its specific position and blur component characteristics. Instead of uniform processing, each image receives tailored correction parameters calculated from its distance from the light axis, ensuring that local variations in image quality are appropriately compensated while maintaining high defect identification accuracy across the entire inspection area.
3Measurement precision
If blur correction is applied to each inspection image, then the defect detection accuracy is improved, but the processing time increases
Solution Approach 1:
The patent calculates and determines the blur components for each inspection image in advance, before the actual defect detection process. By pre-processing the blur correction parameters and organizing them systematically, the system minimizes the time required during the main inspection workflow, thus improving defect detection accuracy while limiting the additional processing time incurred.
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 enhances the accuracy of defect detection by standardizing blur levels across inspection images, reducing false positives and improving the reliability of defect identification in multibeam inspection systems.
Implementation Method 1
apparatuses which inspect masks and templates used in manufacturing of semiconductor devices include an apparatus that uses charged particles such as electron beams
Implementation Method 2
An electron beam is divided by predetermined apertures to generate a multibeam
Implementation Method 3
single beams constituting the multibeam are affected by different aberrations depending on the transmission position (distance from the center) at an objective lens
Data Source
AI summary
There is provided an inspection method that includes determining, as a reference blur component, the magnitude of the blur component of a range, the range being a range where a number of first inspection images among the plurality of inspection images falling within the range is the largest among a plurality of ranges. The inspection method includes correcting, based on the reference blur component, a second inspection image among the plurality of inspection images having the magnitude of the blur component falling outside the range. The inspection method includes comparing the first inspection image and the corrected second inspection image with a reference image, the first inspection image having the magnitude of the blur component falling within the predetermined range, the reference image being generated in advance for the measurement object.