Undercut Geometry for Dual Beam Slice and View Redeposition
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Solution Overview
Problem
Redeposition of ablated material during the slice and view technique in electron microscopy obstructs the view of the sample face, leading to poor image resolution and invalidation of 3D reconstruction data.
Innovation Solution
Creating an undercut beneath the area of interest in the sample substrate to trap and collect ablated material, preventing redeposition and ensuring unobstructed imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the FIB performs the milling operation to remove substrate material, then the face is exposed for imaging, but ablated material redeposits on the face obscuring it
Solution Approach 1:
The patent introduces a spatial dimension by creating an undercut geometry beneath the face. The undercut extends in the depth dimension (z-axis) below the face level, providing a three-dimensional space that collects redeposited material away from the imaging surface. This dimensional extension resolves the contradiction by adding a collection zone that does not interfere with the two-dimensional imaging plane.
Solution Approach 2:
The undercut acts as an intermediary structure between the milling zone and the imaging face. It serves as a intermediate space that captures and holds the ablated material, preventing direct redeposition onto the face. This intermediary zone decouples the harmful redeposition effect from the imaging surface while maintaining the necessary milling function.
2Loss of information
If sequential slicing is performed to obtain deeper cross-sections, then more 3D data is acquired, but image quality deteriorates due to accumulated redeposition
Solution Approach 1:
The undercut is created in advance, before the sequential slicing and imaging process begins. This preliminary preparation establishes a permanent collection zone that will capture all subsequent redeposited material throughout the entire slicing sequence. By preparing this protective structure beforehand, the method prevents image quality deterioration across multiple imaging steps without requiring intervention between slices.
Solution Approach 2:
The patent segments the sample preparation process into distinct functional zones: the imaging face, the undercut collection zone, and the milling zone. This segmentation allows the redeposition phenomenon to be isolated to a specific region (the undercut) that does not interfere with the imaging function. Each slice can be imaged independently with consistent quality because the segmentation prevents cross-contamination between slicing and imaging operations.
3Ease of operation
If the SEM beam axis is at an acute angle to the FIB beam axis, then access to the face is improved, but redeposition increases
Solution Approach 1:
The undercut introduces a depth dimension that separates the beam access geometry from the redeposition problem. The angled beam configuration can maintain its advantageous access geometry while the undercut provides a three-dimensional collection space that captures material regardless of the beam angle. This dimensional separation allows the angled configuration to function without suffering from increased redeposition.
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 enhances the acquisition of high-quality 3D data by maintaining clear images of the sample face, reducing noise and improving the accuracy of 3D representations.
Implementation Method 1
The FIB cuts and slices the sample with high precision to reveal its 3D internal structures or features
Implementation Method 2
particles of the remnant material may redeposit on the face of the feature to be imaged
Data Source
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AI summary
A method is provided for slice and view processing of samples with dual beam systems. The slice and view processing includes providing a location for particles and material resulting from the slice and view process to collect without obscuring the sample face to be viewed and imaged. This location is formed as an undercut located beneath or in front of the sample face.