TEM Sample Preparation Using Arc-Groove FIB Thickness Control
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Solution Overview
Problem
Existing methods for preparing TEM samples lack accuracy in controlling the thickness, often resulting in excessively thin or thick samples that affect analysis quality.
Innovation Solution
A method involving two stages of focused ion beam (FIB) cutting is employed, where the first stage forms an arc-shaped groove in a metal protective layer, and the second stage adjusts the cutting rate based on the changing thickness of the layer to achieve a continuously varying sample width, ensuring an optimal observation area for TEM analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness determination is based on worker experience, then the preparation process is simple, but the thickness control accuracy is poor resulting in excessively thin or thick samples
Solution Approach 1:
The patent introduces a metal protective layer as an intermediary element with varying thickness that serves as a reference standard during FIB cutting. This layer acts as a mediator between the cutting process and the final sample thickness, enabling precise thickness control without requiring complex real-time measurement systems. The metal protective layer's known thickness profile allows operators to achieve accurate sample thickness by referencing this intermediate standard.
2Manufacturing precision
If the metal protective layer thickness is uniform, then the cutting process is simple, but the TEM sample width cannot be precisely controlled
Solution Approach 1:
The patent applies local quality by creating a metal protective layer with non-uniform, gradually varying thickness across different regions. This spatial variation in the protective layer thickness allows different portions of the TEM sample to have different widths, enabling precise local control of sample dimensions. The arc-shaped groove pattern creates a thickness gradient that directly translates to controlled width variation in the final sample.
Solution Approach 2:
The patent utilizes curved, arc-shaped grooves in the metal protective layer to create a gradual thickness transition. This curvature enables continuous variation in the protective layer thickness, which in turn produces smooth width transitions in the TEM sample. The arc shape provides a mathematically predictable thickness profile that facilitates precise width control during the FIB cutting process.
3Manufacturing precision
If the FIB cutting rate is constant, then the cutting process is efficient, but the sample thickness cannot be adjusted to obtain optimal observation areas
Solution Approach 1:
The patent performs preliminary action by pre-forming the metal protective layer with a specific thickness profile before the FIB cutting process. This pre-prepared reference structure allows the cutting process to proceed efficiently with constant or near-constant rates, while still achieving precise thickness control. The thickness information is encoded in advance in the protective layer structure, eliminating the need for complex real-time rate adjustments.
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 allows for precise control of the TEM sample thickness, eliminating defects of excessive thickness or thinness, thereby improving analysis quality.
Implementation Method 1
performing the second time of FIB cutting on the chip sample using the FIB
Data Source
AI summary
The present application discloses a method for preparing a TEM sample, comprising: step 1, step 1, providing a chip sample having a metal protective layer formed on a first surface; step 2, fixing the chip sample on a sample table of a FIB system; step 3, performing the first time of FIB cutting on the metal protective layer along a first direction, so as to form a groove, wherein the first direction is the width direction of the TEM sample, and the inner side surface of the groove is arc-shaped so that the thickness of the metal protective layer in a groove area gradually changes; and step 4, performing the second time of FIB cutting along a third direction to thin the chip sample and form the TEM sample, wherein the third direction is a direction from the metal protective layer to the chip sample.