Multiple Electron Beam Inspection Reference Image Correction
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Solution Overview
Problem
In multiple electron beam inspection systems, maintaining consistent inspection sensitivity across different electron beams is challenging due to variations in imaging characteristics, requiring individual parameter calculations and filter function determinations for each beam, which is computationally intensive and difficult to adapt to characteristic differences.
Innovation Solution
A multiple electron beam inspection apparatus and method that includes a secondary electron image acquisition mechanism, a reference image generation circuit to create reference images based on design data, a correction circuit to adjust reference images based on deviation information between electron beams, and a comparison circuit to compare secondary electron images with corrected reference images, allowing for adaptive matching of electron beam characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple electron beams are used for inspection, then inspection coverage and efficiency are improved, but maintaining consistent inspection sensitivity across different beams becomes difficult due to variations in imaging characteristics
Solution Approach 1:
The patent applies parameter changes by adjusting imaging parameters (such as focus, stigmation, and beam conditions) for each electron beam to compensate for characteristic differences. This allows each beam to produce images with consistent quality and sensitivity levels despite inherent variations in beam characteristics, thereby resolving the contradiction between using multiple beams for efficiency and maintaining uniform inspection sensitivity.
2Measurement precision
If individual parameter calculations and filter function determinations are performed for each electron beam, then inspection sensitivity consistency is improved, but computational complexity and processing time increase significantly
Solution Approach 1:
The patent implements universality by creating a master filter function that can be applied across all electron beams. Instead of calculating individual filter functions for each beam, the system determines one master filter function that captures the essential imaging characteristics, which then serves all beams. This reduces computational complexity while maintaining the ability to compensate for beam-specific variations through the correction image generation process.
3Measurement precision
If individual parameter calculations are performed for each electron beam, then inspection sensitivity consistency is improved, but processing time and computational resources are consumed excessively
Solution Approach 1:
The patent applies preliminary action by determining the master filter function in advance before actual inspection operations. This pre-calculated filter function is then reused for generating reference images and correcting images from multiple beams during inspection. This approach eliminates the need for time-consuming individual parameter calculations during runtime, significantly reducing processing time while maintaining inspection sensitivity consistency.
4Measurement precision
If reference images are generated individually for each electron beam, then inspection accuracy is improved, but the amount of calculation and data processing becomes unmanageably large
Solution Approach 1:
The patent implements copying by generating a single correction image from the master filter function that can be applied to all electron beams. Instead of creating and processing individual reference images for each beam, the system creates one correction image that captures the necessary adjustments for all beams. This dramatically reduces the amount of data to be processed and stored while maintaining the ability to correct for beam-specific characteristics across all inspection images.
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
Enables efficient generation of reference images adapted to characteristic differences between electron beams, reducing computational complexity and maintaining consistent inspection sensitivity, thereby improving the accuracy of pattern defect detection in ultrafine semiconductor patterns.
Implementation Method 1
a secondary electron image acquisition mechanism acquiring secondary electron images of figure patterns by irradiating a substrate formed with the figure patterns with multiple primary electron beams and detecting multiple secondary electron beams emitted from the substrate in accordance with the irradiation of the multiple primary electron beams
Data Source
AI summary
According to one aspect of the present invention, a multiple electron beam inspection apparatus includes a reference image generation circuit generating reference images corresponding to the secondary electron images, in accordance with an image generation characteristic of a secondary electron image by irradiation of one beam; and a correction circuit generating corrected reference images in which, on the basis of deviation information between a figure pattern of the secondary electron image by irradiation of the one beam of the multiple primary electron beams and a figure pattern of a secondary electron image by irradiation of another beam different from the one beam of the multiple primary electron beams, a shape of a figure pattern of a reference image corresponding to the figure pattern of the secondary electron image by the irradiation of the another beam in the reference images is corrected.