Manipulator End Effector for In Situ Electron Diffraction
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Solution Overview
Problem
Current methods for analyzing the crystalline structure of small features in scanning electron microscopes lack sufficient spatial resolution, particularly for irregular specimens, and are inefficient in forensic or failure analysis, as they require elaborate sample preparation and transfer, which can lead to contamination and reduced accuracy.
Innovation Solution
A method involving a manipulator end effector that can rotate and translate a sample within a vacuum chamber to achieve a predetermined geometry for electron diffraction pattern analysis, allowing for in situ collection of diffraction patterns without transferring the sample to a specimen stage, using a combination of focused particle beam isolation and manipulation to orient the sample effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional EBSD methods are used with high tilt angle geometry, then pattern contrast is improved, but spatial resolution deteriorates by a factor of 3
Solution Approach 1:
The patent implements dynamic adjustment of the sample tilt angle during analysis. The manipulator can change the tilt angle from the conventional high angle (e.g., 70 degrees) to lower angles (e.g., 10-30 degrees), allowing optimization between pattern contrast and spatial resolution based on the specific analytical requirements. This dynamic adjustment resolves the contradiction by making the system adaptable rather than fixed at the suboptimal high-tilt configuration.
Solution Approach 2:
The patent changes the geometric parameters of the diffraction geometry by adjusting the tilt angle and using different camera positions. This allows the system to operate in multiple geometric configurations (e.g., symmetric, asymmetric, or transmission geometry) rather than being constrained to a single high-tilt configuration, thereby resolving the trade-off between contrast and resolution through parameter optimization.
2Reliability
If samples are transferred to specimen stages for analysis, then analysis can be performed, but contamination risk increases and efficiency decreases
Solution Approach 1:
The patent merges the sample preparation function and the analysis function into a single integrated system. The manipulator performs both sample isolation from the bulk material and positioning for diffraction analysis without requiring sample transfer to a separate specimen stage. This integration eliminates the contamination risk associated with transfer operations and improves efficiency by combining multiple operations into one continuous process.
Solution Approach 2:
The manipulator system is self-sufficient, performing all necessary operations (isolation, manipulation, positioning, and analysis) within the vacuum chamber without requiring external intervention or sample transfer. The system serves itself by maintaining the sample in the vacuum environment throughout the entire process, eliminating exposure to contamination during transfer operations.
3Measurement precision
If conventional EBSD with X-ray analysis is used, then chemical element identification is improved, but spatial resolution deteriorates due to large X-ray signal volume
Solution Approach 1:
The patent dynamically adjusts the electron beam parameters and manipulator positioning to optimize the overlap between the electron beam interaction volume and the X-ray detector collection volume. By controlling the sample geometry and orientation in real-time, the system ensures that both EBSD and X-ray signals originate from the same small region, resolving the spatial resolution mismatch between the two techniques.
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 high-resolution electron diffraction pattern analysis with improved spatial resolution, reducing contamination risks and increasing efficiency by preparing and analyzing the sample within the vacuum chamber, allowing for precise crystalline structure determination and chemical elemental analysis without the need for elaborate sample mounting.
Implementation Method 1
electrons travelling in very specific directions will be reflected from crystalline planes. An electron backscatter diffraction (EBSD) pattern may be obtained using a geometry that is typically as shown in FIG. 1 where the pattern is formed from electrons scattered from just beneath the specimen surface that are Bragg-diffracted by crystalline layers within tens of nanometres of the specimen surface.
Implementation Method 2
a focussed particle beam is used to isolate part of a specimen to form a sample. The particle beam may be an ion beam or a laser beam. In one embodiment the particle beam is a focussed ion beam and part of the specimen is isolated by milling.
Implementation Method 3
A method involving a manipulator end effector that can rotate and translate a sample within a vacuum chamber to achieve a predetermined geometry for electron diffraction pattern analysis
Implementation Method 4
At each point on the raster, an electron detector is used to record the varying signal due to electrons that have been scattered or emitted from the specimen and thus form an image of the rastered field of view.
Data Source
AI summary
A method is provided for performing electron diffraction pattern analysis upon a sample in a vacuum chamber of a microscope. Firstly a sample is isolated from part of a specimen using a focused particle beam. A manipulator end effector is then attached to the sample so as to effect a predetermined orientation between the end effector and the sample. With the sample detached, the manipulator end effector is rotated about a rotation axis to bring the sample into a predetermined geometry with respect to an electron beam and diffraction pattern imaging apparatus so as to enable an electron diffraction pattern to be obtained from the sample while the sample is still fixed to the manipulator end effector. An electron beam is caused to impinge upon the sample attached to the manipulator end effector so as to obtain an electron diffraction pattern.