Positive-tone photoresists based on tin-oxo nanoclusters for electron-beam and extreme UV lithography

초록

Conventional chemically-amplified resist (CAR) processing relies on Brønsted-Lowry-type acid-base reactions to enable tone control through aqueous versus organic solvent development. Here, we show that an analogous, expanded acid-base chemistry framework can be applied to tin-oxo nanocluster (TOC) photoresists by employing Lewis acid-base coordinative interactions. To regulate coupling between TOCs following ionizing radiation-induced dissociation of alkyl ligands, we introduce a dendritic polyphenol, DHP, that provides both Lewis basicity and Brønsted acidity as a second formulation component. Under ionizing radiation, DHP is proposed to coordinate to ligand-dissociated, Lewis-acidic Sn centers, modulating inter-TOC bond formation and thus development behavior. Using a standard tetramethylammonium hydroxide (TMAH) aqueous developer, the TOC-DHP films yield positive-tone patterns (PTD), whereas development in a reduced-polarity organic solvent produces negative-tone patterns (NTD). These findings demonstrate that established CAR processing concepts can be extended to TOC-based resist systems by broadening the scope of acid-base chemistry, providing a practical route to increased process latitude and more versatile development pathways for EUV lithography. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

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