Charged Particle Beam Drift Tracking for 3D Tomography Imaging
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Solution Overview
Problem
Current charged particle beam (CPB) systems require excessive time to image large volume samples at high resolution, and are prone to sample drift due to mechanical and thermal variations, limiting their efficiency in capturing detailed images of large areas.
Innovation Solution
A selective high-resolution imaging method that acquires low-resolution images of large sample areas, allowing operators to identify regions of interest (ROI) for high-resolution imaging, using a CPB workstation to control the beam and stage for precise targeting and efficient data acquisition, while incorporating features like alignment notches for milling rate adjustment and drift compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution imaging is applied to large volume samples, then image quality is improved, but imaging time increases excessively
Solution Approach 1:
The patent divides the large volume sample into multiple smaller sub-volumes or regions of interest (ROIs). The imaging system acquires images of these segmented regions separately and combines them to form a complete high-resolution 3D reconstruction. This segmentation allows the system to maintain high resolution while reducing the total imaging time by focusing computational and imaging resources on smaller manageable regions rather than processing the entire large volume at once.
2Area of stationary object
If imaging is performed over extended periods to capture large areas, then coverage is improved, but sample drift increases due to mechanical and thermal variations
Solution Approach 1:
The patent incorporates feedback mechanisms where the system continuously monitors the positions of fiducial markers or alignment features across multiple imaging sessions. This positional information is fed back to update and refine the transformation matrices that map between different coordinate systems. The feedback loop enables real-time compensation for drift, ensuring that images acquired over extended periods remain accurately aligned despite mechanical and thermal variations in the imaging environment.
Solution Approach 2:
The patent employs preliminary actions by embedding fiducial markers or alignment features into the sample before imaging begins. These pre-placed references serve as stable reference points that can be detected across multiple imaging sessions. By having these alignment features prepared in advance, the system can quickly establish coordinate transformations and compensate for drift without requiring time-consuming real-time calibration procedures during the imaging process.
3Adaptability or versatility
If multiple charged particle beams are used for 3D analysis, then imaging capability is improved, but drift tracking complexity increases
Solution Approach 1:
The patent implements a universal drift tracking approach where a single coordinate transformation framework is developed that can handle multiple charged particle beams (such as electron beams and ion beams) simultaneously. The system uses a common set of fiducial markers and a unified transformation matrix calculation method that works across different beam types. This universal approach allows the system to maintain improved imaging capability through multi-beam operation while avoiding the complexity that would arise from developing separate drift tracking systems for each beam type.
Data Source
AI summary
A method to compensate for drift while controlling a charged particle beam (CPB) system having at least one charged particle beam controllable in position. Sources of drift include mechanical variations in the stage supporting the sample, beam deflection shifts, and environmental impacts, such as temperature. The method includes positioning a sample supported by a stage in the CPB system, monitoring a reference fiducial on a surface of the sample from a start time to an end time, determining a drift compensation to compensate for a drift that causes an unintended change in the position of a first charged particle beam relative to the sample by a known amount over a period of time based on a change in the position of the reference fiducial between the start time and the end time, and adjusting positions of the first charged particle beam by applying the determined drift compensation during an operation of the CPB system.