Sample Orientation Workflow for EBSD-SACP Crystal Alignment
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Solution Overview
Problem
Existing charged particle microscopy methods struggle to accurately and efficiently determine crystal orientation, particularly in polycrystalline materials, as electron backscatter diffraction (EBSD), electron channeling patterns (ECP), and selected area electron channeling patterns (SACP) provide incomplete information and require precise alignment for effective electron channeling contrast imaging (ECCI).
Innovation Solution
A method involving initial alignment using EBSD followed by refinement with SACP to achieve high angular accuracy, utilizing a retractable 2D pixelated BSE detector for EBSD and an annular BSE detector for SACP, with an electronic controller adjusting sample orientation based on acquired patterns to align the sample into the Bragg condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If EBSD is used for crystal orientation determination, then the angular range coverage is comprehensive, but the angular resolution and accuracy are reduced
Solution Approach 1:
The patent segments the crystal orientation determination process into two distinct stages: first using EBSD to capture comprehensive angular range and identify approximate orientation, then using SACP to refine the measurement with high angular resolution. This segmentation allows each method to operate in its optimal performance range, resolving the contradiction between comprehensive coverage and high precision.
Solution Approach 2:
The patent applies preliminary action by using EBSD to obtain preliminary crystal orientation information before proceeding to the refinement stage with SACP. The EBSD pattern acquisition and initial orientation determination serve as a preparatory step that guides the subsequent high-precision SACP measurement, ensuring both comprehensive coverage and high accuracy are achieved.
2Measurement precision
If SACP is used for crystal orientation determination, then the angular resolution and accuracy are improved, but the angular range coverage is limited
Solution Approach 1:
The patent segments the measurement process so that SACP is applied only after EBSD has established the preliminary orientation. This segmentation allows SACP to focus on refining the angular resolution within a narrowed angular range, while EBSD provides the comprehensive angular coverage that SACP alone cannot achieve.
Solution Approach 2:
The patent uses EBSD as a preliminary action to establish the crystal orientation within a wide angular range before applying SACP for high-precision refinement. This preliminary orientation determination enables SACP to operate effectively within a constrained angular range, maximizing its angular resolution capabilities.
3Device complexity
If manual sample orientation adjustment is used, then the equipment complexity is reduced, but the time consumption and operational efficiency increase
Solution Approach 1:
The patent implements feedback mechanisms where the electronic controller continuously monitors EBSD and SACP patterns, automatically adjusts sample orientation based on the acquired diffraction patterns, and iteratively refines the crystal orientation determination. This closed-loop feedback system eliminates manual intervention, significantly reducing time consumption while managing system complexity through automated control algorithms.
Solution Approach 2:
The patent enables the system to perform self-service by automatically determining crystal orientation and adjusting sample position without human intervention. The electronic controller autonomously processes diffraction patterns, calculates orientation parameters, and commands manipulator movements, making the system self-sufficient in the crystal orientation determination process.
4Loss of time
If automated crystal orientation determination is implemented, then the time consumption is reduced, but the device complexity increases
Solution Approach 1:
The patent achieves time reduction by implementing a universal automated system that integrates multiple functions: EBSD pattern acquisition, SACP pattern acquisition, crystal orientation determination, and sample position control all within a single automated workflow. The electronic controller serves multiple purposes, managing both diffraction pattern analysis and manipulator coordination, thereby reducing overall process time while consolidating complexity into a multi-functional platform.
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 rapid and precise determination of crystal orientation, allowing for high-contrast imaging of lattice defects through ECCI, enhancing the accuracy and efficiency of sample alignment in charged particle microscopy.
Implementation Method 1
acquiring an electron backscatter diffraction pattern (EBSD) with one or more detectors when an electron-beam column is operated to direct an electron beam at a first impact point within a region of interest (ROI) of a sample
Implementation Method 2
acquire a first selected area electron channeling pattern (SACP) of the ROI placed in the second crystal orientation with the one or more detectors when the electron beam is operated to rock the electron beam at a second impact point within the ROI
Data Source
AI summary
In some embodiments, a scientific instrument includes a manipulator configured to controllably rotate a sample, an electron-beam column configured to direct an electron beam to a selected impact point on the sample; and a detector configurable to detect an angularly resolved pattern and a flux of back-scattered electrons. The scientific instrument also includes an electronic controller configured to: determine a first crystal orientation of the sample based on the angularly resolved pattern acquired when the electron-beam column is operated to keep the electron beam fixed at the impact point; operate the manipulator to place the sample into a second crystal orientation in which an angular difference between the determined first crystal orientation and a target crystal orientation is estimated to be canceled; and determine the second crystal orientation based on an SACP acquired when the electron-beam column is operated to rock the electron beam at the impact point.