Atom Probe Tomography Reconstruction Using Real Tip Geometry
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Solution Overview
Problem
Existing atom probe tomography methods struggle with inaccurate reconstruction of three-dimensional atomic distributions due to assumptions of axial symmetry and hemispherical tip shapes, particularly in heterogeneous samples, leading to errors in tip shape estimation.
Innovation Solution
A method and system for determining three-dimensional atomic distribution by recording hit maps, dividing them into zones, identifying mass-to-charge ratios, deriving flight lengths and launch angles, and matching approximate to actual surface geometries, without assuming axial symmetry, using scanning probe microscopy or other techniques for precise tip shape measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If axial symmetry and hemispherical tip shape assumptions are made, then reconstruction complexity is reduced, but measurement precision of three-dimensional atomic distribution deteriorates
Solution Approach 1:
The patent uses scanning probe microscopy to create a physical copy/measurements of the actual tip shape, which is then used in the reconstruction algorithm. This measured tip geometry serves as a template that replaces the need for simplifying assumptions, allowing accurate reconstruction without requiring complex iterative shape determination.
Solution Approach 2:
The tip shape is measured and characterized before the atom probe tomography reconstruction process. This preliminary measurement of the actual tip geometry provides accurate initial parameters for the reconstruction algorithm, eliminating the need to solve for tip shape during reconstruction and thereby reducing complexity while maintaining precision.
2Ease of operation
If simplifying assumptions of axial symmetry are made, then ease of operation is improved, but reliability of reconstruction for heterogeneous samples deteriorates
Solution Approach 1:
The actual tip shape is copied through physical measurement using scanning probe microscopy. This measured geometry is then used in the reconstruction algorithm, providing reliable results for heterogeneous samples without requiring axial symmetry assumptions. The copied real geometry maintains ease of operation while improving reliability.
3Measurement precision
If detailed tip shape measurement methods are employed, then measurement precision of tip geometry is improved, but device complexity increases
Solution Approach 1:
Scanning probe microscopy serves as an intermediary tool that measures the tip shape independently. This measured geometry then acts as a mediator input for the atom probe tomography reconstruction algorithm. This intermediary measurement approach achieves high precision without directly complicating the reconstruction system itself.
Solution Approach 2:
The tip shape is measured in advance using scanning probe microscopy before the atom probe tomography reconstruction. This preliminary measurement separates the complex shape determination from the reconstruction process, achieving high precision while keeping the reconstruction algorithm itself relatively simple by providing pre-determined accurate geometry.
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
Achieves highly accurate reconstruction of three-dimensional atomic distributions by accounting for real tip shapes, reducing errors associated with simplifying assumptions, and providing precise spatial positioning of atoms.
Implementation Method 1
A high electric field (>10 V/nm) is thereby induced at the apex of the tip such that the atoms at the surface of the apex are ionized
Implementation Method 2
a laser pulse is added to trigger the evaporation process by supplying additional thermal energy such that the atoms at the apex can overcome the energy barrier of evaporation
Implementation Method 3
Evaporated ions are detached from the tip surface and are accelerated towards the detector according to the electric field distribution between the tip and the detector
Implementation Method 4
The TOF is measured as the time difference between the arrival time (on the detector) and the onset of a voltage pulse or laser pulse which triggers the evaporation process. By analyzing the time of flight of the atoms, the mass-to-charge ratio of the species can be determined
Data Source
AI summary
A method for determining a three-dimensional atomic distribution of a sample having a tip, during an atom probe tomography process. The method accounts for the tip not being axial symmetric and not having a hemispherical shaped apex throughout the evaporation process.