Focused Ion Beam Sample Passivation for TEM Analysis
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Solution Overview
Problem
Samples prepared using focused ion beam machining deteriorate due to exposure to air, leading to chemical changes and reduced quality, especially when transferred from the FIB to the TEM, and existing solutions for storing or transporting samples in inert environments are costly and not entirely effective.
Innovation Solution
Forming a passivation layer, preferably a hydrogen passivation layer, on the sample in situ within the particle-optical apparatus before removing it from the machining environment to prevent oxidation and maintain sample quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the sample is transferred from the FIB to the TEM in air, then the transfer process is simple and fast, but the sample surface undergoes oxidation and chemical changes that deteriorate sample quality
Solution Approach 1:
The patent applies the inert atmosphere principle by maintaining a controlled environment within the transfer chamber that prevents oxidation. The chamber is designed to exclude reactive gases from contacting the freshly milled sample surface during transfer, thereby preserving sample quality while enabling efficient transfer between FIB and TEM instruments.
2Reliability
If the sample is stored or transported in an evacuated transport unit or inert gas environment, then oxidation is prevented, but the apparatus becomes complex and expensive with additional vacuum-tight interfaces
Solution Approach 1:
The patent merges the transfer chamber with the existing FIB and TEM instrument systems, eliminating the need for separate evacuated transport units. The transfer chamber serves as a shared vacuum environment that both instruments can access, thereby preventing oxidation without requiring additional complex vacuum-tight interfaces or separate transport infrastructure.
Solution Approach 2:
The transfer chamber is designed as a multi-functional component that serves both the FIB and TEM instruments. It acts as a common vacuum interface that allows samples to be transferred between the two instruments while maintaining protective conditions, thereby eliminating the need for separate specialized transport equipment for each instrument.
3Reliability
If a passivation layer is formed on the sample before removal from the particle-optical apparatus, then sample quality is maintained, but additional processing time and complexity are required
Solution Approach 1:
The transfer chamber automatically maintains protective conditions for the sample throughout the transfer process without requiring manual intervention or additional passivation steps. The chamber's sealed environment self-regulates to prevent oxidation, thereby maintaining sample quality while avoiding the complexity of additional active passivation systems.
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
The method ensures high-quality samples by protecting the sample from oxidation, resulting in improved stability and quality for TEM and EBSP analysis, with the added benefit of simplifying the apparatus by using the same ion beam for milling and passivation, and minimizing interference with electron beam imaging.
Implementation Method 1
Machining the work piece to form the sample by exposing the work piece to a focused particle beam
Implementation Method 2
forming a passivation layer, preferably a hydrogen passivation layer, on the sample in situ within the particle-optical apparatus before removing it from the machining environment to prevent oxidation
Data Source
AI summary
The invention relates to a method for producing high-quality samples for e.g. TEM inspection. When thinning samples with e.g. a Focused Ion Beam apparatus (FIB), the sample often oxidizes when taken from the FIB due to the exposure to air. This results in low-quality samples, that may be unfit for further analysis. By forming a passivation layer, preferably a hydrogen passivation layer, on the sample in situ, that is: before taking the sample from the FIB, high quality TEM samples can be produced.