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Preparation of Nanoparticles for ToF-SIMS and XPS Analysis
Published on: September 13, 2020
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ToF-SIMS analysis of ultrathin films and their fragmentation patterns
Shin Muramoto1, Daniel J Graham, David G Castner
1National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
Journal of Vacuum Science & Technology. A, Vacuum, Surfaces, and Films : an Official Journal of the American Vacuum Society
|February 8, 2024
Summary
Characterizing ultrathin organic films (1-20 nm) using plasma polymerization reveals unique spectral trends. Thinner films show increased carbon contamination and fragmentation, differing from thicker samples.
Area of Science:
- Materials Science
- Surface Science
- Analytical Chemistry
Background:
- Organic thin films are crucial for electronic devices like transistors and sensors.
- Characterizing ultrathin films (near single nanometer) presents significant analytical challenges.
- Understanding film properties at the nanoscale is key for device performance.
Purpose of the Study:
- To investigate the impact of film thickness on spectral data of ultrathin plasma polymers.
- To analyze how cross-linking and thickness affect characterization using time-of-flight secondary ion mass spectrometry (TOF-SIMS).
- To identify unique spectral features and interpretation challenges for films between 1-20 nm.
Main Methods:
- Plasma polymerization was employed to synthesize organic films with thicknesses ranging from 1 to 20 nm.
- Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was utilized for spectral analysis.
- Principal component analysis (PCA) was coupled with TOF-SIMS to interpret spectral variations.
Main Results:
- For ultrathin (1-20 nm) cross-linked plasma polymers, spectral trends differ from thicker films.
- Ambient carbon contamination increasingly dominates the mass spectrum with decreasing thickness.
- Cluster-induced nonlinear enhancement in secondary ion yield was not observed; fragmentation increased due to primary ion energy confinement.
- Primary ion source size (e.g., Bi1 vs. Bi5) was found to influence fragmentation patterns.
Conclusions:
- Data interpretation for ultrathin organic films requires careful consideration of thickness-dependent effects.
- The choice of primary ion source is critical for accurate fragmentation analysis in TOF-SIMS of thin films.
- Observed trends highlight the complexity of analyzing nanoscale organic materials, necessitating specific analytical strategies.
