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Preparation of Sample Support Films in Transmission Electron Microscopy using a Support Floatation Block
Published on: April 8, 2021
Back-etch method for plan view transmission electron microscopy sample preparation of optically opaque films.
1Advanced Materials Processing and Analysis Center, and Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA. bo555252@pegasus.cc.ucf.edu
Journal of Electron Microscopy
|January 30, 2008
Summary
A new back-etching method uses optical reflection contrast to precisely stop etching for preparing opaque thin film transmission electron microscopy (TEM) samples, preventing perforation and ensuring high-quality imaging.
Area of Science:
- Materials Science
- Surface Science
- Analytical Chemistry
Background:
- Back-etching is standard for TEM sample prep, removing Si substrates.
- Conventional methods fail for opaque films (>75 nm) due to lack of color change.
- Film perforation is a common issue with opaque samples.
Purpose of the Study:
- Introduce a novel back-etching endpoint determination method for opaque thin films.
- Enable precise TEM sample preparation for films thicker than 75 nm.
- Prevent film perforation during the etching process.
Main Methods:
- Utilized an optical reflection contrast change to signal etch endpoint.
- Leveraged the interface between the film/SiO2 and the etchant.
- Controlled Si roughness and SiO2 etch rate for optimal results.
Main Results:
- Successfully prepared TEM samples of 100-nm Fe-based alloy and 160-nm Cu films.
- Demonstrated a clear, abrupt change in optical reflection contrast at the etch endpoint.
- Achieved artifact-free TEM samples without perforation.
Conclusions:
- The optical reflection contrast method is effective for opaque thin film TEM sample preparation.
- This technique offers precise control over the etching process.
- It overcomes limitations of traditional color-based methods for opaque samples.
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