Pyramid-Shaped SPM Probe for APT Apex Positioning
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Solution Overview
Problem
Scanning Probe Microscopy (SPM) techniques face challenges in accurately imaging the apex region of needle-shaped samples, such as those used in Atom Probe Tomography (APT), due to distortions caused by tip shape changes and the difficulty in achieving precise relative positioning of the SPM probe and sample tip, especially at the nanoscale.
Innovation Solution
A method and apparatus utilizing a pyramid-shaped SPM probe mounted on a cantilever, with a drive mechanism and detection tools, perform iterative scan movements to accurately position and image the apex region of a needle-shaped sample by interacting with multiple side planes of the probe, allowing for precise determination of the sample tip shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a standard SPM probe is used to image the apex region of a needle-shaped sample, then the imaging process is simple, but the positioning precision between the probe and sample tip deteriorates due to the difficulty of achieving correct relative positioning at the nanometre scale
Solution Approach 1:
A pyramid-shaped intermediate structure with planar faces and edges is introduced as a mediator between the SPM probe and the sample tip. The probe first interacts with the planar faces and detects edges during scanning, which serves as an intermediary step to establish precise spatial relationship before imaging the actual sample apex, thereby solving the positioning precision problem while maintaining operational simplicity
Solution Approach 2:
The method performs preliminary scanning actions where the probe first interacts with the pyramid structure's planar faces and detects its edges to establish correct relative positioning. This preliminary positioning action is performed before the actual imaging of the sample apex, ensuring precise alignment is achieved in advance
2Measurement precision
If the SPM probe interacts with the sample tip apex directly, then the imaging is direct, but the positioning accuracy deteriorates because both the sample tip and probe tip have nanometre-scale dimensions making correct relative positioning difficult
Solution Approach 1:
The imaging process is segmented into two distinct phases: first interacting with the pyramid structure's planar faces and edges for positioning, then imaging the sample apex. This segmentation allows the system to separately handle the positioning challenge and the imaging task, improving overall measurement precision while reducing the complexity of relative positioning
Solution Approach 2:
The pyramid structure serves as an intermediary object that facilitates precise positioning. By detecting edges during scanning of this intermediate structure, the system establishes accurate spatial relationships before imaging the actual sample, thereby reducing the difficulty of direct nanometre-scale positioning
3Measurement precision
If iterative scan movements are performed to achieve precise positioning, then the positioning accuracy improves, but the time required for imaging increases
Solution Approach 1:
The pyramid structure's geometric features (planar faces and edges) provide self-aligning characteristics that guide the probe to the correct position automatically during scanning. This self-service mechanism reduces the need for extensive iterative adjustments, improving positioning accuracy while minimizing the time penalty
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
Enables accurate imaging of the apex region of needle-shaped samples, reducing distortions and improving the precision of 3D reconstructions in APT by effectively aligning and scanning the SPM probe relative to the sample tip, even at the nanoscale.
Implementation Method 1
A method for determining, by applying Scanning Probe Microscopy (SPM), the shape of the apex region of the free-standing tip of a needle-shaped sample
Data Source
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AI summary
The invention is related to a method and apparatus for correctly positioning a probe (1) suitable for scanning probe microscopy (SPM) relative to the apex region (21) of a needle-shaped sample (11), such as a sample for atom probe tomography, in order to perform an SPM acquisition of said apex region to thereby obtain an image of said region. The positioning takes place by an iterative process, starting from a position wherein one side plane (12) of the pyramid-shaped SPM probe interacts with the sample tip (15). By controlled consecutive scans in two orthogonal directions, the SPM probe tip (1) approaches and finally reaches a position wherein a tip area (H) of the probe interacts with the sample tip's apex region (21).