Multi-Beam Pattern Inspection Image Correction for False Defect Reduction
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Solution Overview
Problem
Existing pattern inspection apparatuses using multiple electron beams face challenges in accurately comparing inspection images due to shape and size differences between beams, leading to false defects and reduced inspection accuracy.
Innovation Solution
A pattern inspection apparatus and method that includes a secondary electron image acquisition mechanism, storage device for individual correction kernels, and a comparison circuit to adjust and align inspection images using correction kernels to match a reference blurred image, ensuring uniformity across different beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple electron beams are used for inspection, then inspection speed and productivity are improved, but beam uniformity deteriorates causing shape and size differences between beams
Solution Approach 1:
The patent changes the parameters of the electron beams by applying individual correction kernels to each beam's inspection image. These kernels adjust the shape and size parameters of each beam's image to match a reference beam, thereby achieving uniformity across multiple beams while maintaining high inspection speed
Solution Approach 2:
The patent performs preliminary correction of beam differences by generating and applying correction kernels before the actual inspection comparison. This preliminary action ensures that all beams are standardized to reference conditions, eliminating the need for repeated adjustments during inspection
2Measurement precision
If inspection images from different beams are compared directly, then inspection accuracy should be high, but false defects occur due to beam characteristic differences
Solution Approach 1:
The patent introduces a reference beam's inspection image as an intermediary standard. All other beam images are corrected to match this reference, allowing accurate comparison without direct beam-to-beam variation. This intermediary reference eliminates false defects caused by beam characteristic differences
Solution Approach 2:
The patent creates corrected copies of inspection images from different beams by applying correction kernels. These corrected copies are made to match the reference beam's characteristics, enabling accurate comparison while eliminating the harmful effects of original beam variations
3Shape
If correction kernels are applied to each beam, then beam uniformity is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality correction by using individual correction kernels for each beam rather than a universal correction method. Each kernel is tailored to the specific characteristics of its corresponding beam, achieving precise uniformity with minimal overall complexity
Solution Approach 2:
The correction kernels are generated and applied in advance before the main inspection process. This preliminary preparation reduces the complexity during actual inspection, as the correction step becomes a straightforward application of pre-computed kernels rather than complex real-time processing
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 accurate inspection by aligning inspection images acquired with different beams to a common condition, reducing false defects and enhancing the precision of pattern defect detection.
Implementation Method 1
a deflector which deflects multiple primary electron beams
Implementation Method 2
detecting the multiple secondary electron beams emitted from the surface of the target object
Implementation Method 3
a correction circuit configured to correct, by correspondingly using the individual correction kernel, the secondary electron image corresponding to the each primary electron beam
Data Source
AI summary
A pattern inspection apparatus includes a secondary electron image acquisition mechanism to include a deflector deflecting multiple primary electron beams and a detector detecting multiple secondary electron beams, and acquire a secondary electron image corresponding to each of the multiple primary electron beams by scanning a target object with a pattern thereon with the multiple primary electron beams by the deflector, and detecting the multiple secondary electron beams from the target object by the detector, a storage device to store individual correction kernels each generated for individually adjusting a secondary electron image corresponding to each primary electron beam concerning a reference pattern to be commensurate with a reference blurred image, and a correction circuit to correct, by correspondingly using the individual correction kernel, the secondary electron image corresponding to each primary electron beam acquired from the inspection target object.