Charged Particle Beam Tilt Control Using Diffraction Scans
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Solution Overview
Problem
When observing a specimen using a charged particle beam device like a scanning transmission electron microscope (STEM) or a transmission electron microscope (TEM), aligning the specimen orientation with the electron beam incident orientation is crucial for accurate length measurements. However, continuous emission of the electron beam for orientation adjustment can cause specimen damage and contamination, especially in specimens with complex structures or when using high-current beams, leading to blurred interfaces and reduced accuracy.
Innovation Solution
A charged particle beam device with a movement mechanism, particle source, detector, and controller that adjusts the specimen tilt by acquiring diffraction patterns at different illumination positions, minimizing specimen damage by scanning a wider illumination region and using a single crystal region for pattern acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electron beam is continuously emitted to adjust specimen orientation, then the orientation adjustment accuracy is improved, but the specimen damage and contamination increase
Solution Approach 1:
The patent applies periodic action by controlling the electron beam to be emitted intermittently rather than continuously during diffraction pattern acquisition. The beam is emitted only when needed for capturing diffraction patterns at different illumination positions, with periods of non-emission in between, thereby reducing cumulative specimen damage while still achieving accurate orientation adjustment through multiple discrete measurements
Solution Approach 2:
The patent segments the orientation adjustment process into multiple discrete steps, each involving emission of the electron beam only when needed to capture a diffraction pattern at a specific illumination position. Instead of continuous emission, the beam is emitted in segmented bursts corresponding to specific measurement moments, reducing overall exposure time and specimen damage while maintaining measurement precision
2Measurement precision
If the electron beam size is reduced to illuminate only the crystal region, then the diffraction pattern quality is improved, but the acquisition time increases
Solution Approach 1:
The patent introduces a temporal dimension to the measurement process by acquiring diffraction patterns at multiple different illumination positions sequentially over time. Instead of attempting to capture all necessary information in a single long exposure, the system takes multiple shorter measurements at different positions and combines them, reducing specimen damage per measurement while achieving comprehensive orientation data through the added temporal and spatial dimensions
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 reduces specimen damage and contamination while enabling precise orientation adjustment, ensuring clear diffraction patterns and accurate length measurements.
Implementation Method 1
a particle source configured to output a charged particle beam
Implementation Method 2
acquires a diffraction pattern... based on a detection result of the detector
Data Source
AI summary
Provided is a charged particle beam device that includes a movement mechanism configured to hold and move a specimen, a particle source configured to output a charged particle beam, a detector configured to detect a signal generated by illuminating the specimen with the charged particle beam, and a controller configured to control the movement mechanism, the particle source, and the detector. The controller determines an illumination target region in the specimen according to the specimen, moves an illumination position of the charged particle beam in the illumination target region, and acquires a diffraction pattern according to a detection result of the detector at different illumination positions, and controls the movement mechanism based on an analysis result of the diffraction pattern to adjust tilt of the specimen.