Electron-Transparent Sample Prep With Intact Surface Preservation
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Solution Overview
Problem
Existing sample preparation methods for correlative characterisation, such as those used for polycrystalline thin films, often result in ion beam-induced damage and are time-consuming, requiring transfer between instruments, and fail to preserve the sample surface for subsequent characterisation.
Innovation Solution
A method involving milling the second face of a sample to create a trench that provides an electron transparent layer while preserving the surface region of interest, allowing for in-situ characterisation within the same instrument, using techniques like transmission Kikuchi diffraction to obtain nanoscale crystallographic information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional FIB lift-out techniques are used to prepare electron transparent samples, then electron transparent samples can be obtained for TEM characterisation, but the sample surface is damaged by ion beam and time is consumed for transfer between instruments
Solution Approach 1:
The sample preparation process is segmented into two distinct operations: (1) milling the second face to create a trench and expose the electron transparent sample layer, and (2) preserving the first face with its intact surface region. This segmentation allows the electron transparent region and the intact surface region to coexist on the same sample, enabling correlative characterisation without ion beam damage to the surface.
Solution Approach 2:
The invention accesses the electron transparent sample layer from a different dimension by milling the second face of the sample rather than the first face. This dimensional approach allows the electron beam to transmit through the thinned region while the original surface on the first face remains intact and undamaged, solving the contradiction between obtaining electron transparency and preserving surface integrity.
2Manufacturing precision
If FIB lift-out techniques are used for sample preparation, then electron transparent samples can be obtained, but the preparation process is time consuming and requires transfer between instruments
Solution Approach 1:
The sample preparation method is self-sufficient and can be completed entirely within the FIB-SEM instrument. The trench milling process automatically exposes the electron transparent sample layer in situ, eliminating the need for time-consuming manual lift-out operations and transfer to TEM. The instrument performs both the preparation and subsequent characterisation functions internally.
Solution Approach 2:
The invention merges the sample preparation function and the characterisation function into a single integrated process within the FIB-SEM. By milling the trench and exposing the electron transparent layer in the same instrument that performs subsequent electron beam characterisation, the method eliminates separate transfer steps and reduces total preparation time while maintaining high precision.
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 minimises sample damage and preparation time, enabling high-resolution correlative characterisation of both electron transparent and intact surface regions, suitable for samples of any thickness, without the need for transfer between instruments.
Implementation Method 1
milling the second face of the sample to provide a trench in the surface of the second face
Implementation Method 2
milling the second face of the sample to provide a trench in the surface of the second face
Implementation Method 3
the trench is arranged so as to provide an electron transparent sample layer comprising the surface region of interest
Data Source
AI summary
The invention relates to a method of preparing a sample for analysis. The method comprises: providing a sample comprising a surface region of interest on a first face of the sample and a second face oriented at an angle to the first face about a common edge between the first and second faces, the second face extending between the common edge and a second edge on the opposing side of the second face of the sample; and milling the second face of the sample to provide a trench in the surface of the second face, the trench extending from a first position on the second face between the common edge and the second edge to a second position adjacent to the common edge; wherein the trench is arranged so as to provide an electron transparent sample layer comprising the surface region of interest. By milling the second face of the sample only, a surface region of interest on the first face of the sample is fully preserved and remains free of milling beam induced damage. This allows for correlative characterisation work which requires both an electron transparent sample and a fully intact sample surface to obtain surface-sensitive data.