Alkenyl-type ligands functionalized tin-lanthanide oxo nanoclusters as molecular lithography resists

Both the cluster chemistry of tin and lanthanides have attracted extensive research interest, showing wide applications in catalysis, magnetism, luminescence, and lithography. However, their fusion into heterometallic Sn-Ln oxo clusters is still to be explored. In this study, through the stabilization of alkenyl-type cis -5-norbornene-endo-2,3-dicarboxylic acid (H 2 NE) ligands, a series of atomically precise Sn-Ln oxo nanoclusters have been successfully constructed from the assembly of heterometallic tetranuclear Sn x Ln (4− x ) building blocks. Thereinto, Sn 12 Eu 8 and Sn 13 Er 6 with the highest nuclearities are built from multiple assembly of 8 {Sn 2 Eu 2 } units and 6 {Sn 3 Er} and {Sn 2 Er 2 } units, respectively. ESI-MS analysis indicates that Sn 13 Er 6 has high solution stability, allowing their packing into thin films for lithography applications. As a result of electron beam lithography (EBL) studies, the condensation of Sn 13 Er 6 can be triggered by low energy radiation of 10 µC/cm 2 , and 50 nm lines have been fabricated at expose energy of 50 µC/cm 2 , confirming the satisfying sensitivity and resolution of Sn 13 Er 6 . Hence, the success of this study develops the chemistry of heterometallic tin-lanthanide clusters that can be applied as novel negative photoresist materials.