Performance Optimization of Sulfonium-Functionalized Molecular Resists for EUV and Electron Beam Lithography

We report the synthesis and lithographic evaluation of a series of sulfonium-functionalized molecules nonchemically amplified resists (n-CARs) designed for high-resolution lithography. These molecular resists, built upon a rigid adamantane core, feature varied substitution positions (meta or para), side chains (methoxy or butoxy), and counteranions (CF₃SO₃^–, BF₄^–, PF₆^–, and SbF₆^–). Our study highlights that meta-substitution and the incorporation of flexible butoxy side chains significantly enhance the film quality and lithographic performance. Notably, the ADMBu-TF resist, functionalized with CF₃SO₃^– and meta-substituted butoxy chains, exhibits the best lithographic performance. Using extreme ultraviolet lithography, we achieved 15 nm line/space (L/S) patterns with a line-edge roughness of 2.2 nm, positioning this resist as a promising candidate for next-generation lithographic processes.