Sample Orientation Alignment Using EBSD and SACP Refinement
Find Innovative SolutionsGenerate Solutions
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 for precise ECCI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If EBSD is used for initial alignment, then alignment speed is improved, but alignment precision deteriorates
Solution Approach 1:
The patent applies preliminary action by using EBSD for initial alignment to quickly bring the sample into approximate orientation, then using SACP for refinement to achieve high precision. This two-stage approach performs the rough alignment in advance, allowing the subsequent precision step to focus only on fine adjustments.
Solution Approach 2:
The alignment process is segmented into two distinct stages: initial alignment using EBSD and refinement alignment using SACP. Each stage uses the most appropriate technique for its specific purpose, combining the speed advantage of EBSD with the precision advantage of SACP.
2Measurement precision
If SACP is used for precise alignment, then alignment precision is improved, but alignment time increases
Solution Approach 1:
By performing initial alignment with EBSD first, the patent reduces the starting error for the SACP refinement stage, allowing SACP to achieve high precision more quickly than if it had to work from a poorly aligned starting position.
Solution Approach 2:
The alignment task is divided into segments where EBSD handles the coarse alignment portion and SACP handles the fine refinement portion, optimizing the time investment at each stage.
3Productivity
If multiple detectors are used for simultaneous EBSD and SACP, then measurement efficiency is improved, but device complexity increases
Solution Approach 1:
The patent employs a multi-functional detector system where a single pixelated BSE detector can operate in different modes (EBSD mode and SACP mode) by adjusting its position and the electron beam configuration, eliminating the need for separate dedicated detectors for each technique.
Solution Approach 2:
The patent combines EBSD and SACP capabilities into a single integrated measurement system using one pixelated BSE detector that can be repositioned and reconfigured, merging the functionality of what would traditionally require separate detection systems.
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 accurate determination of crystal orientation with an accuracy of approximately 0.1 degrees, allowing for high-contrast imaging of lattice defects through ECCI, enhancing defect visualization in scanning electron microscopy (SEM).
Implementation Method 1
an angularly resolved pattern of back-scattered electrons emitted from the selected impact point in response to the electron beam
Implementation Method 2
selected area electron channeling pattern (SACP) acquired with the one or more detectors
Data Source
Figure 1
Figure 2
Figure 3
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.