Correlative S/TEM and APM Sample Preparation via Lamella Reshaping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current correlative transmission electron microscopy (S/TEM) and atom probe microscopy (APM) tomography face challenges with pillar-shaped samples, including lower data quality due to sample thickness and feature-obscuring projection effects, uncontrollable evaporation, and limitations in data analysis volume, which hinder optimal material analysis and compatibility with advanced imaging techniques.
Innovation Solution
A method is developed to prepare a sample with a thin lamella containing a region of interest (ROI) that can be reshaped into a needle-shaped sample for APM analysis, allowing for site-specific S/TEM and APM analysis with improved data quality and correlation between S/TEM and APM data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pillar-shaped samples are used for correlative S/TEM and APM tomography, then both structural and compositional data can be obtained, but data quality is reduced due to sample thickness and feature-obscuring projection effects in S/TEM
Solution Approach 1:
The sample preparation process is segmented into distinct stages: first creating a thin lamella for optimal S/TEM imaging, then reshaping it into a pillar for APM analysis. This segmentation allows each technique to operate on the sample in its optimal form, avoiding the compromise of using a single pillar shape for both techniques.
Solution Approach 2:
The sample undergoes a dimensional transformation from a flat two-dimensional lamella to a three-dimensional pillar structure. This dimensionality change enables the sample to be optimized for S/TEM imaging in its flat state and then reconfigured for APM analysis in its pillar form, resolving the contradiction between the two techniques' requirements.
2Reliability
If pillar-shaped samples are used for APM analysis, then compositional data can be obtained, but evaporation becomes uncontrollable leading to artifacts and catastrophic fracture
Solution Approach 1:
The lamella is prepared with controlled thickness and uniform composition before being shaped into a pillar. This preliminary preparation ensures that when the pillar undergoes field evaporation in APM, the process is more predictable and controllable, reducing uncontrollable evaporation events and artifacts.
Solution Approach 2:
The sample's physical parameters are changed during preparation - specifically its thickness and compositional uniformity are controlled during lamella formation. These parameter changes make the subsequent field evaporation process more stable and controllable, improving reliability while maintaining ease of operation.
3Area of stationary object
If pillar-shaped samples are used for correlative tomography, then both S/TEM and APM analysis are possible, but the field of view is limited to approximately the inner 50% of the pillar
Solution Approach 1:
The region of interest is extracted and isolated as a thin lamella from the bulk material, then reshaped into a pillar. This extraction allows the entire lamella to be utilized for APM analysis, effectively increasing the usable field of view beyond the inner 50% limitation of conventional pillars, while maintaining efficient data acquisition.
4Measurement precision
If advanced S/TEM imaging and analytical techniques are used, then high-resolution structural data can be obtained, but compatibility with pillar-shaped samples is largely incompatible
Solution Approach 1:
The sample shape is made dynamic rather than fixed - it transitions from a flat lamella optimized for advanced S/TEM techniques to a pillar shape for APM analysis. This dynamic adaptability allows high-resolution structural data to be obtained using advanced S/TEM techniques on the lamella, then the same sample can be reconfigured for APM without compromising either technique's capabilities.
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 S/TEM tilt-series data and minimally distorted APM data, enhancing the accuracy of three-dimensional microstructure and composition analysis by optimizing the sample form for both microscopy techniques and improving field evaporation characteristics.
Implementation Method 1
A sample containing a region of interest (ROI) is cut from a bulk of sample material using a focused ion beam or other method
Implementation Method 2
material is deposited onto the thin lamella to form a thicker structure with the lamella embedded
Implementation Method 3
The thicker structure is then milled to form a needle-like structure for atom probe microscopy
Implementation Method 4
An electrical pulse and/or laser pulse is intermittently applied to the sample to cause atoms at the tip of the needle to ionize and separate or 'evaporate' from the sample
Data Source
AI summary
A method of forming a sample and performing correlative S/TEM and APM analysis is provided wherein a sample containing a region of interest is cut from a bulk of sample material and formed into an ultra-thin lamella. The lamella is then analyzed with an S/TEM to form an image. The lamella sample and mount may then go through a cleaning process to remove any contamination. The lamella containing the ROI is then embedded within a selected material and is formed into a needle-shaped sample. The needle-shaped sample is then analyzed with the APM and the resulting data is merged and correlated with the S/TEM data.