We apply near-edge x-ray absorption fine structure (NEXAFS) spectroscopy to quantify the surface composition and depth profiling of photoacid generators in thin film photoresist materials by varying the entrance-grid bias of the photoelectron detector. By considering model compositional profiles, NEXAFS distinguishes the surface molar excess within the top 6 nm from the bulk. A surface enriched system, triphenylsulfonium perfluorooctanesulfonate, is contrasted with a perfluorobutanesulfonate photoacid generator, which displays an appreciable surface profile to the bulk within a 6 nm segregation length scale. These results, while applied to 193-nm photoresist materials, highlights a general approach to quantifying NEXAFS experimental data.
Citation: Applied Surface Science
Pub Type: Journals
immersion lithography, lithography, photoresist, segregation, spectroscopy, thin film