Atomically Precise Interfacial Engineering on Tin-Silicon Oxo Clusters for Sub-8 nm Lithography

Tin oxo clusters (TOCs) have been recognized as the most promising photoresist candidates for high numerical aperture extreme ultraviolet (High-NA EUV) lithography. To enhance the adhesion between the exposed cluster species and the silicon dioxide substrate, herein, we incorporate silane moieties to functionalize the surface of TOCs for the first time. By synergistically integrating the high radiation sensitivity of Sn and substrate affinity of Si, ultrahigh resolution patterning at the sub-8 nm scale has been successfully achieved, which represents the best performance in TOC photoresists. Multiple spectroscopic analyses and theoretical calculations on reaction mechanisms indicate that the incorporated Si moieties function dually by capturing scattered secondary electrons (SEs) to produce silyl radicals that guide the formation of dense Si-O-Si structure, while simultaneously enhancing interfacial adhesion to the SiO₂ substrate. Such a synergistic process yields diverse and abundant Sn-O-Sn/Sn-O-Si/Si-O-Si networks, collectively realizing higher resolution and lower line-edge roughness (LER). This work not only introduces a new family of Sn-Si oxo cluster resists but also demonstrates the potential of atomic-level interfacial engineering for next-generation ultrahigh-resolution semiconductor manufacturing technologies.