SEM Image Acquisition Device Rotating Scan Direction
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Solution Overview
Problem
Existing SEM image acquisition methods face challenges when measuring two-dimensional patterns, particularly with circular and inclined patterns, as the electron beam's scanning direction affects signal quality and edge detection, leading to reduced signals and 'black lines' due to charging issues, making accurate contour extraction and measurement difficult.
Innovation Solution
An SEM image acquisition device and method that rotates the electron beam's scanning direction to align with pixel correspondence, allowing for the synthesis of images from different scanning directions, ensuring that signals are acquired and processed from the same positions on the sample, thereby improving measurement accuracy and reducing charging effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electron beam scanning direction is fixed, then the acquisition time is short, but the measurement precision deteriorates due to reduced signals and black lines at pattern edges
Solution Approach 1:
The patent divides the image acquisition process into multiple segments by scanning the electron beam in different directions (e.g., 0° and 45°) and then synthesizing the results. This segmentation allows each scan to capture different edge orientations, improving overall measurement precision without requiring excessive time investment in any single direction.
Solution Approach 2:
The patent employs periodic scanning actions where the electron beam systematically scans the sample in predetermined directions at different angles. This periodic multi-directional scanning ensures comprehensive coverage of pattern edges while maintaining efficient time management through structured scan sequences.
2Measurement precision
If the scanning direction is rotated to align with pattern edges, then the signal quality improves, but the pixel alignment between different scanning directions becomes misaligned
Solution Approach 1:
The patent creates multiple copies of the scanned image data from different scanning directions and then synthesizes them. By treating each directional scan as a separate copy that can be independently processed and then combined, the system maintains pixel alignment accuracy while benefiting from the improved signal quality of rotated scanning directions.
3Measurement precision
If multiple images from different scanning directions are synthesized, then the measurement accuracy improves, but the device complexity increases
Solution Approach 1:
The patent implements a universal synthesis process that can handle multiple scanning directions and pattern types through a single integrated algorithm. This multi-functional approach allows the same synthesis mechanism to process images from various directional scans, improving measurement accuracy while avoiding the need for separate complex processing systems for each scan direction.
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 enables high-accuracy edge extraction and measurement in any direction, including circular and inclined patterns, by synthesizing images from multiple scanning directions, improving the signal-to-noise ratio and maintaining the same acquisition time as conventional methods, while ensuring consistent emission conditions and pixel alignment.
Implementation Method 1
acquire an image by emitting an electron beam on a sample and detecting electrons emitted or reflected from or absorbed by the sample
Implementation Method 2
a deflection device configured to emit the electron beam on a position on the sample corresponding to the same region and the same pixels on the sample, on the basis of the scanning signal generated by the scanning signal generation unit
Data Source
AI summary
An SEM image acquisition device including a scanning signal generation unit configured to rotate a scanning direction of the electron beam to be scanned on the sample and generate a scanning signal to be emitted on a position on the sample corresponding to a same region and same pixels on the sample; a deflection device configured to emit the electron beam on a position on the sample corresponding to the same region and the same pixels on the sample, on the basis of the scanning signal generated by the scanning signal generation unit; a detection and amplification unit configured to detect and amplify a signal from the position on the sample corresponding to the same region and the same pixels on the sample, on which the electron beam was emitted by being deflected by the deflection device; and an image generation unit configured to generate an image from when the position on the sample corresponding to the same region and the same pixels on the sample is irradiated, on the basis of the signal detected and amplified by the detection and amplification unit.