Balancing sensitivity and resolution by feedback regulation of free radicals from Sn-C bonds in tin-oxygen clusters EBL photoresist

Notably, the cleavage of Sn–C bonds in extreme-ultraviolet photoresists containing Sn-oxygen (oxo) clusters and the generation of free radicals upon exposure lead to the chemical linking of Sn-oxo cores and subsequent solubility shifts. The reactivities and migration patterns of the generated radicals substantially influence patterning outcomes, including sensitivity and resolution. Herein, two Snoxo clusters, Sn₄-Me-C₁₀ (with Sn–methyl) and Sn₄-Bu-C₁₀ (with Sn–butyl), were combined to balance the sensitivity and resolution of photoresists, leveraging the feedback regulation between methyl and butyl free radicals generated from Sn–C bond cleavage. During electron beam lithography exposure, sensitive butyl radicals produced by Sn₄-Bu-C₁₀ initiated reactions within Sn₄-Me-C₁₀, improving sensitivity. Subsequently, the unstable methyl and bulky adamantyl radicals generated by Sn₄-Me-C₁₀ quenched the excess butyl radicals, thus improving the resolution and exposure latitude. Thus, this method leveraging the feedback regulation of free radicals offers new insights into the design of sensitive metal oxide resists with enhanced resolution.