ToF-SIMS Analysis of Ultrathin Films and Their Fragmentation Patterns

Published

February 8, 2024

Author(s)

Shin Muramoto, Daniel Graham, David Castner

Abstract

Organic thin films are of great interest due to their intriguing interfacial and functional properties, especially for device applications such as thin-film transistors and sensors. As their thickness approaches single nanometer thickness, characterization and interpretation of the extracted data become increasingly complex. In this study, plasma polymerization is used to construct ultrathin films that range in thickness from 1 to 20 nm, and time-of-flight secondary ion mass spectrometry coupled with principal component analysis is used to investigate the effects of film thickness on the resulting spectra. We demonstrate that for these crosslinked plasma polymers, at these thicknesses, the observed trends are different from those obtained from thicker films with lower degrees of crosslinking: contributions from ambient carbon contamination starts to dominate the mass spectrum; cluster induced non-linear enhancement in secondary ion yield is no longer observed; extent of fragmentation is higher due to confinement of the primary ion energy; and the size of the primary ion source also affects fragmentation (e.g., Bi1 vs Bi5). These differences illustrate that care must be taken in choosing the correct primary ion source as well as in interpreting the data.

Citation

Journal of Vacuum Science & Technology A

Pub Type

Journals

Keywords

ToF-SIMS, thin films, plasma polymerization, tetraglyme, cluster sources

Citation

Muramoto, S. , Graham, D. and Castner, D. (2024), ToF-SIMS Analysis of Ultrathin Films and Their Fragmentation Patterns, Journal of Vacuum Science & Technology A (Accessed April 27, 2024)