Laser Trepanning for TEM Sample Preparation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for preparing electron-transparent samples for transmission electron microscopy are time-consuming and cause damage to materials, especially when attempting to achieve thin samples with large material depths and high spatial resolution.
Innovation Solution
A method involving helical drilling or trepanning techniques, where a high-energy beam is used to create intersecting indentations on both sides of a plane-parallel disc, followed by additional ion beam etching, to achieve thin, electron-beam-transparent samples with improved mechanical stability and reduced processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional mechanical grinding and ion beam etching methods are used to prepare electron-transparent samples, then sample thickness can be reduced to achieve electron beam transparency, but processing time increases significantly (4-5 hours to a day) and material damage occurs
Solution Approach 1:
The patent replaces traditional mechanical grinding methods with laser-based ablation technology. The laser beam directly ablates material to create indentations and thin sections, eliminating the need for mechanical contact and multiple grinding steps. This substitution dramatically reduces processing time from hours to minutes while maintaining precise thickness control through laser parameter adjustment.
Solution Approach 2:
The patent utilizes controllable laser parameters (power, pulse duration, scanning speed, beam diameter) to precisely control the ablation process. By adjusting these parameters, the laser can remove material at controlled rates to achieve the exact thickness required for electron beam transparency, replacing the trial-and-error nature of traditional mechanical methods with precise parameter-based control.
2Manufacturing precision
If focused ion beam (FIB) methods are used to prepare thin samples, then sample thickness can be precisely controlled (50-100 nm), but ion beam implantation causes material damage and falsification
Solution Approach 1:
The patent replaces the focused ion beam method with a laser ablation system. Instead of using ion beams that implant and damage material, the laser uses photothermal and photomechanical effects to ablate material cleanly. This substitution eliminates ion implantation damage while maintaining the ability to achieve precise thicknesses through controlled laser parameters and multi-pass ablation strategies.
3Area of stationary object
If mechanical cutting and plane-parallel grinding are used to prepare samples, then large sample areas can be obtained, but sample thickness cannot be uniformly reduced to electron beam transparency without extensive additional processing
Solution Approach 1:
The patent divides the sample preparation process into two stages: first, mechanical methods create a large-area thin disc with approximate thickness; second, laser ablation creates localized indentations and further thins specific regions to the precise thickness required for electron beam transparency. This segmentation allows the final sample to have both large area (from the initial disc) and precise thickness uniformity (from the laser processing).
Solution Approach 2:
The patent performs preliminary mechanical thinning to create a large-area disc reduced to approximately 100 microns thickness before applying laser ablation. This preliminary action removes the bulk of the material thickness, making the subsequent laser processing more efficient and enabling the laser to achieve the final electron beam transparent thickness more quickly and uniformly across the sample area.
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 method allows for the rapid preparation of thin samples with minimal damage, enabling the analysis of materials at deeper depths and larger volumes, significantly reducing processing time compared to existing techniques while maintaining high accuracy and precision.
Implementation Method 1
a flat, plane-parallel disc is irradiated with a laser beam along both of its opposite surfaces in such a way that a running indentation is introduced into these two surfaces by material removal caused by the laser beam
Implementation Method 2
a further thinning step is required, which is usually carried out, for example, by inert gas-based (e.g. with argon ions) ion beam etching
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to a method for the preparation of a sample for microstructure diagnostics, in particular for transmission electron microscopy TEM, scanning electron microscopy or X-ray absorption spectroscopy, wherein a flat, preferably plane-parallel plate is irradiated along each of the two opposite surfaces thereof with a high-energy beam such that, as a result of radiation-induced material removal, there is formed in each of said two surfaces a depression which runs preferably parallel to a central plate plane, wherein said two depressions are formed, so as to run at both sides of said/a central plate plane, such that the longitudinal axes thereof, as viewed in a projection of said longitudinal axes onto said central plate plane, intersect at a predefined angle a > 0°, preferably a = 10°, preferably a = 20°, preferably a = 30°, and that, in the region of intersection of the two depressions, a material portion which is preferably transparent to electron beams and which is of predefined minimum thickness as viewed perpendicular to said central plate plane remains between said depressions as a sample. The invention also relates to a correspondingly designed device.