Regulation and Synthesis of Mixed-Ligand Titanium-Oxide Nanoparticles for 12 nm Nanolithography

The rapid advancement of extreme UV lithography has intensified the demand for photoresist (PR) innovation, with organic-inorganic hybrid metal oxide photoresists (MORs) emerging as a promising next-generation platform. The design of organic ligands in MORs is crucial, as these functional ligands tailor the physical, chemical, and optical properties of the PR to meet the stringent resolution, roughness, and sensitivity requirements of advanced lithography. Herein, a mixed-ligand strategy is reported for high-resolution nanolithography using titanium-oxide (TiO₂) PR functionalized with benzoic acid and fluorobenzoic acid ligands. Upon radiation exposure, the electron-triggered decarboxylation of these ligands, combined with fluorinated groups, initiates new reaction pathways, including C─F bond cleavage and Ti─F structure formation. These pathways drive the solubility transition of the nanoparticles during development, resulting in a negative pattern. Evaluated via electron beam lithography, these mixed-ligand-modified TiO₂ PRs achieve high-quality lines with feature sizes down to 12 nm and line width roughness of ≈1.3 nm, a substantial improvement over monoligand benzoic acid systems under identical conditions. These results demonstrate the effectiveness of the mixed-ligand strategy in enhancing the imaging capability of MORs and provide valuable insights for further development in advanced lithography.