EUV-induced activation mechanism of photoacid generators: key factors affecting EUV sensitivity

Ji Young Park; Thanh Cuong Nguyen; Deakeon Kim; Hyun-Ji Song; Suk Koo Hong; Won-Joon Son; Hyoshin Ahn; Inkook Jang; Dae Sin Kim

doi:10.1117/12.2652345

30 April 2023 EUV-induced activation mechanism of photoacid generators: key factors affecting EUV sensitivity

Ji Young Park, Thanh Cuong Nguyen, Deakeon Kim, Hyun-Ji Song, Suk Koo Hong, Won-Joon Son, Hyoshin Ahn, Inkook Jang, Dae Sin Kim

Author Affiliations +

Proceedings Volume 12498, Advances in Patterning Materials and Processes XL; 124980T (2023) https://doi.org/10.1117/12.2652345
Event: SPIE Advanced Lithography + Patterning, 2023, San Jose, California, United States

Abstract

Theoretical lithography performance prediction of photoresist material has important role to design better material but the exact prediction was still difficult because there are too many conditions to be considered together. We investigated the EUV-induced photochemical reactions of conventional triphenylsulfonium (Ph₃S⁺; TPS) PAG-cation in both “electron-trapping” and “internal excitation” mechanisms using atomic-scale materials modeling. By obtaining full energy profiles of protonation process of TPS molecule, we could find that the acid generation yield strongly depends on two main factors: the LUMO of PAG-cation in which the lower LUMO of PAG-cation, the reduction step of PAG-cation is easier and the proton (H⁺) dissociation ability (pKa) at the ortho-positions of thiol ether fragment cation(Ph₂S⁺), in which lower pKa will give high acid generation. By matching computational analysis with experimental results, we developed a two-parameter model to predict the EUV exposure Dose from the target PAG–cation’s LUMO and pKa of thiol ether-derivatives. We applied our new model to other three sets of TPS samples and they also shows good correlation with experimental data. Finally, we proposed a strategy to design new PAG molecules for sensitivity improvement by functionalization of TSP-cation with electron donating group. Our new strategy can be a powerful tool to design novel PAG cation for EUV photoresist for improving Resolution-LER-Sensitivity trade-off.

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Citation Download Citation

Ji Young Park, Thanh Cuong Nguyen, Deakeon Kim, Hyun-Ji Song, Suk Koo Hong, Won-Joon Son, Hyoshin Ahn, Inkook Jang, and Dae Sin Kim "EUV-induced activation mechanism of photoacid generators: key factors affecting EUV sensitivity", Proc. SPIE 12498, Advances in Patterning Materials and Processes XL, 124980T (30 April 2023); https://doi.org/10.1117/12.2652345

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