A positive-tone extreme ultraviolet (EUV) photoresist was obtained via the exchange of the hydroxide ions of tin-oxo-hydroxo cages with tetrakis(pentafluorophenyl)-borate. Thin films were obtained after spin coating on silicon substrates and exposed to line patterns in interference lithography at 92 eV (13.5 nm). For low doses and development with ethylbenzene positive tone patterns were obtained. In contrast, the exchange of the hydroxide ions of tin-oxo-hydroxo cages with tetrakis(4-methylphenyl)-borate or tetrakis[3,5-bis(1,1,1,3,3,3-hexafluoro-2-methoxy-2-propyl)phenyl]-borate led to the negative-tone photoresist behaviour that has previously been observed for tin-oxo cages with all other counterions. In situ exposures at 92 eV and subsequent X-ray Photoelectron Spectroscopy were performed on a film of tin-oxo-hydroxo cages with tetrakis(pentafluorophenyl)-borate anions to probe the chemical changes induced by the EUV exposure. This shows that the C-F bonds of the anions are relatively stable.

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European Union's Horizon 2020 , ASML, ARCNL, VU, UvA, RUG, NWO
J. Photopolym. Sci. Technol.
Nanophotochemistry-Former Group

Evrard, Q., Sadegh, N., Ekinci, Y., Vockenhuber, M., Mahne, N., Giglia, A., … Brouwer, A. (2022). Influence of Counteranions on the Performance of Tin-based EUV Photoresists. J. Photopolym. Sci. Technol., 35(1), 95–100. doi:10.2494/photopolymer.35.95