Dissociative photoionization of phenyl triflate, a photoacid generator for photolithography, at 92 eV

V Laffert; F S Sajjadian; R Richter; M J van Setten; F Holzmeier

doi:10.1063/5.0203648

Dissociative photoionization of phenyl triflate, a photoacid generator for photolithography, at 92 eV

J Chem Phys. 2024 Apr 7;160(13):134303. doi: 10.1063/5.0203648.

Authors

V Laffert^{1

2}, F S Sajjadian^{1

3}, R Richter⁴, M J van Setten¹, F Holzmeier¹

Affiliations

¹ Imec, Kapeldreef 75, B-3001 Leuven, Belgium.
² Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
³ Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
⁴ Elettra-Sincrotrone Trieste, Area Science Park, Basovizza, I-34149 Trieste, Italy.

PMID: 38557851
DOI: 10.1063/5.0203648

Abstract

The dissociative photoionization of phenyl triflate (C6H5OSO2CF3), a neutral photoacid generator used in photolithography, was investigated in a gas phase experiment employing extreme ultraviolet (EUV) synchrotron radiation at 92 eV and photoelectron-photoion coincidence detection. The interaction of EUV photons with the molecule leads almost exclusively to dissociation, which is dominated by a sequential fragmentation mechanism, in which SO2, CF3, CO, and C2H2 are lost. For lithographic purposes, the lack of the observation of a fragment that could serve as a precursor for the formation of triflic acid means that the effective photoacid generator concentration in a photoresist is reduced, impacting its patterning performance in EUV lithography. A better understanding of the dissociative photoionization of photoresist components and proxies thereof can provide a crucial handle that guides the design of photoresists for the upcoming technology nodes with ever decreasing feature sizes for more powerful computer chips.