Improving the Lithographic Performance of Tetranuclear Organotin Resist via Additives with Active Ligands ^†

Comprehensive Summary A series of tetranuclear organotin clusters (Sn‐mCl, Sn‐opy, Sn‐mMe, and Sn‐dMe) with different carboxylate ligands (mCl, meta ‐chloromethylbenzoate; opy, picolinate; mMe, meta ‐methylbenzoate; dMe, 3,5‐dimethylbenzoate) were synthesized and characterized. Evaluations on thermostability and film‐forming capability demonstrate the potential of Sn‐opy cluster and the mixture of Sn‐opy with Sn‐mCl cluster additive ( m 1 / m 2 = 9 : 1, designated as Resist‐91) as negative‐tone non‐chemically amplified resist (n‐CAR) materials. The lithographic performances of Resist‐91 and Sn‐opy resist were evaluated by using electron beam lithography. Sn‐opy resist can only resolve the best 22 nm half‐pitch (HP) pattern at 2000 μC·cm –2 . Resist‐91 exhibits superior lithographic performance and resolves 20 nm HP patterns at 1450 μC·cm –2 , demonstrating a significantly improving of the sensitivity and resolution by the introduction of Sn‐mCl. Further extreme ultraviolet lithography demonstrates the capability of Resist‐91 to form 20 nm HP patterns at a dose of 39 mJ·cm –2 , with the best Z ‐factor of 2.1 × 10 –7 mJ·nm 3 among ladder‐shaped tetranuclear organotin resists. Extensive mechanistic analysis of Resist‐91 and model films demonstrates the substitution of Cl atom by pyridine ligand, and the generation of a network consisting of tin oxides and organics with the assistance of Sn‐mCl cluster, highlighting the critical role of additives with active ligands.