Radiation chemistry of a novel zinc–oxo cluster crosslinking strategy for EUV patterning

Metal oxide-based photoresists are extensively developed due to the mature mechanism of C=C double bond crosslinking reaction. However, such materials require low-temperature and light-shielded storage due to unstable C=C double bond. Herein, the C–F bond crosslinking strategy was first proposed in metal–oxo clusters for lithography patterning. Take the photoresist Zn–TBA for example, it could form smooth and defect-free thin films with the surface roughness R_q being smaller than 0.2 nm. With an Extreme ultraviolet interference mask, the patterns could be resolved into 37.5-nm half-pitch at 65 mJ cm⁻². After being exposed and developed with n-hexane, a negative tone image was observed, and the prominent patterns morphology was confirmed by an atomic force microscope. Importantly, Zn–TBA could be stored at room temperature and bright environment. Besides decarboxylation, we proposed that photoinitiated C–F cross-linking was a major contributor to Zn–TBA patterns, which was convinced by high-resolution X-ray photoelectron spectra and theoretical density functional theory calculations. The novel lithographic mechanism provides excellent insight for the next generation of metal-based materials design.