Charged Particle Beam Sample Tilt Control for Backlash Compensation
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Solution Overview
Problem
Current methods for determining and adjusting the orientation of samples in electron microscopy face challenges due to backlash in sample stages and visual field escape, leading to inaccurate and time-consuming processes, especially when observing sub-nm resolution samples.
Innovation Solution
A charged particle beam device with a control unit that obtains reference and goal images to accurately move the sample through a series of tilt angles, using Homography transformation and correlation values to minimize backlash and visual field escape, enabling high-accuracy sample orientation and positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sample stage is tilted to adjust sample orientation, then the sample orientation accuracy can be improved, but visual field escape occurs and requires repeated correction
Solution Approach 1:
The patent calculates the visual field escape amount in advance based on the tilt angle and applies compensation movement to the sample stage before tilting occurs. This preliminary compensation prevents visual field escape from occurring in the first place, eliminating the need for repeated correction operations after tilting.
Solution Approach 2:
The patent implements a feedback mechanism where the visual field escape amount is calculated based on the tilt angle, and this calculated information is fed back to adjust the sample stage position. The system continuously monitors and compensates for visual field escape by applying corrective movements proportional to the predicted escape amount.
2Measurement precision
If the sample stage tilt is adjusted manually to achieve high orientation accuracy, then the sample orientation can be improved, but the operation complexity increases due to backlash and visual field escape
Solution Approach 1:
The patent enables the system to automatically calculate and compensate for visual field escape without requiring manual intervention. The control unit autonomously determines the escape amount based on tilt angle and applies necessary corrections, making the system self-correcting and eliminating complex manual adjustment operations.
Solution Approach 2:
The patent replaces manual mechanical adjustment operations with an automated calculation and control system. Instead of relying on operators to manually compensate for backlash and visual field escape through repeated adjustments, the system uses computational methods to predict and correct these effects automatically.
3Extent of automation
If the visual field escape is corrected by creating a table of stage movement amounts in advance, then the automation can be improved, but the reproducibility is poor due to backlash
Solution Approach 1:
The patent changes the approach from using fixed pre-calculated tables to dynamically calculating compensation amounts based on actual tilt angles. By making the compensation parameters variable and dependent on the specific tilt operation being performed, the system adapts to each situation rather than relying on predetermined values that don't account for backlash variations.
Data Source
AI summary
A charged particle beam device includes: a movement mechanism configured to hold and move a sample; a charged particle source configured to emit charged particles with which the sample is irradiated to obtain an image of the sample; and a control unit configured to control the movement mechanism to move the sample and to obtain the image of the sample. The control unit obtains a reference image of the sample in a reference arrangement state by the charged particles, generates a goal image of the sample in a target arrangement state different from the reference arrangement state by calculation from the reference image, moves the sample to each of different arrangement states by the movement mechanism, obtains a candidate image of the sample in each of the different arrangement states by the charged particles, and generates a comparison result between respective candidate images and the goal image.