INS1-0310
Molecular Engineering of Organotin Oxide Clusters for High-Sensitivity EUV Photoresists
Topic
S1. Polymer Synthesis
When and Where
Oct 1, 2026
15:50 - 16:15
Room 101
Session Chairs
Byungjin KOO
Presenter(s)
Bongjin Moon (Sogang University)
Co-Author(s)
Abstract
Extreme ultraviolet (EUV) lithography demands photoresists combining high sensitivity, resolution, and etch resistance. Organotin oxide clusters such as the butyltin dodecamer are leading metal-based candidates owing to tin's large EUV absorption cross-section and radical-mediated crosslinking via homolytic Sn–C bond cleavage, but they suffer from poor solubility in process solvents (PGMEA, PGME) and a narrow ligand library imposed by harsh basic syntheses. We present two molecular-design strategies overcoming these limits. First, tin–silicon hybrid oxide clusters were synthesized by mild biphasic condensation of butyltin trichloride with alkyltrichlorosilanes and by acid-catalyzed condensation of butylstannoic acid with triethoxysilane to install Sn–O-Si bonds. ESI-MS confirmed unified tin–silicon oxo cages. Clusters with Sn:Si = 5:5 and 8:2 showed >25 wt% solubility in process solvents and enhanced thermal stability; in electron-beam lithography (25 keV), BuSn-CySi-(8:2) and BuSn-HSi-(9:1) outperformed the butyltin dodecamer in pattern resolution. Second, an ester group was introduced at the β-position of tin: its carbonyl oxygen coordinates to the Lewis-acidic tin center, forming a five-membered stannacycle that weakens the Sn–C bond. A mild biphasic K2CO3 route afforded the first ester-containing organotin oxide cluster (91% yield), characterized by multinuclear NMR, elemental analysis, and ESI-MS. UV irradiation released methyl propionate (GC-MS), confirming homolytic Sn–C cleavage, and FT-IR verified Sn–O–Sn network formation upon post-exposure bake. The cluster dissolved at >20 wt% in PGMEA/PGME without anion exchange, remained stable over four months, and produced 20.6 nm line/space patterns at 1000 μC/cm², surpassing the dodecamer. These results establish metal-composition control and coordinating-ligand design as powerful strategies for next-generation EUV photoresists.
