Photodissociation and electron-collision induced dissociation of C5H2F10 using photoelectron–photoion coincidence spectroscopy and quantum chemistry

The transition to high-aspect-ratio, eco-friendly plasma etching gases with low global warming potential (GWP) is critical for advancing sustainable semiconductor manufacturing. Hence, the dissociative photoionization dynamics of 1,1,1,2,2,3,4,5,5,5-decafluoropentane (C₅H₂F₁₀), a promising alternative to conventional high-GWP perfluorocarbons, were comprehensively investigated. Fragmentation mechanisms were elucidated using an integrated approach combining synchrotron-based photoelectron-photoion coincidence (PEPICO) spectroscopy, electron-impact ionization mass spectrometry, and computational quantum chemistry. In addition to mapping the primary fragments (e.g., C₄H₂F₇⁺, C₃H₂F₅⁺, and CF₃⁺), this study deciphered the complex rearrangement pathways leading to the prominent and persistent CHF₂⁺ ion, which is a key species that cannot be formed by simple bond cleavage. Computational calculations revealed precise fluorine migration steps and energetic barriers, which were conclusively validated by the strong anticorrelation observed in the time-resolved ion yield curves. Exploration of the influence of electron energy on fragmentation demonstrated that lower energies (20 eV) preserve primary dissociation channels, whereas higher energies (70 eV) drive extensive fragmentation. This study provides a strategic framework for optimizing reactive-species fluxes in next-generation etching processes by linking tunable gas-phase dissociation, including controlled CHF₂⁺ generation, under plasma-relevant conditions.