In-situ STEM Sample Preparation Without Flip Stage
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Solution Overview
Problem
Current methods for preparing samples for scanning transmission electron microscopy (STEM) are not site-specific and often require sectioning of the original sample, leading to destruction and the need for additional thinning, which can be time-consuming and require breaking vacuum for repositioning, especially when using dual beam FIB-STEM systems without a flip stage.
Innovation Solution
A method that utilizes a dual beam FIB-STEM system with a typical tilt stage of approximately 60° to extract and mount samples, allowing for sample repositioning to be perpendicular to the electron column for STEM imaging without a flip stage, enabling FIB milling and SEM/STEM imaging from above and through the sample, and achieving electron-transparent thin sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional TEM sample preparation methods are used, then samples can be viewed in transmission electron microscope, but the preparation process is time-consuming and requires breaking vacuum for repositioning
Solution Approach 1:
The patent combines multiple sample preparation steps (extraction, thinning, and mounting) into a single continuous process performed entirely within the FIB-STEM system vacuum chamber, eliminating the need to break vacuum for repositioning samples between different equipment stations
Solution Approach 2:
The FIB-STEM system is used to perform multiple functions sequentially: extracting the sample from the substrate, thinning it to electron-transparent thickness, and mounting it on the TEM grid, all within the same vacuum environment without requiring separate preparation stations
2Measurement precision
If site-specific sample extraction is performed, then specific features can be analyzed, but the sample requires additional thinning and repositioning operations
Solution Approach 1:
The sample is extracted from the substrate at the precise location of interest using FIB milling before any thinning operations, allowing the exact feature of interest to be isolated and prepared for analysis without requiring subsequent repositioning or relocation steps
3Device complexity
If dual beam FIB-STEM system without flip stage is used, then system complexity is reduced, but sample repositioning to perpendicular orientation is difficult
Solution Approach 1:
The patent utilizes the dynamic tilting capability of the FIB-STEM stage to reposition the extracted sample from its initial extraction orientation to the final perpendicular orientation relative to the electron beam, achieving the required sample orientation without requiring a mechanical flip stage
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 accurate and efficient STEM sample preparation and analysis within a dual beam FIB-STEM system without a flip stage, maintaining sample integrity and reducing the need for vacuum breaks, enabling precise imaging and thinning while maintaining the sample's original orientation.
Implementation Method 1
freeing a sample from the substrate using an ion beam; thinning the sample using the ion beam by milling the sample
Implementation Method 2
a primary electron beam is focused to a fine spot, and the spot is scanned across the sample surface. Electrons that are transmitted through the substrate are collected by an electron detector
Data Source
AI summary
A method for TEM/STEM sample preparation and analysis that can be used in a FIB-electron microscope system without a flip stage. The method allows a dual beam FIB electron microscope system with a typical tilt stage having a maximum tilt of approximately 60° to be used to extract a TEM/STEM sample to from a substrate, mount the sample onto a sample holder, thin the sample using FIB milling, and rotate the sample so that the sample face is perpendicular to a vertical electron beam column for TEM/STEM imaging.