Vacuum-processed hybrid resists for advanced lithography: molecular layer deposition and sequential infiltration synthesis

Under next-generation extreme ultraviolet (EUV, 13.5 nm) lithography, conventional organic photoresists face inherent limitations due to their small photon absorption cross-sections, making it difficult to simultaneously achieve high resolution, low line-edge roughness (LER), high sensitivity, and excellent etch resistance. To overcome these challenges, hybrid resists fabricated via molecular layer deposition (MLD) and sequential infiltration synthesis (SIS)-both derived from atomic layer deposition-have recently been introduced. MLD enables molecular-level control over organic-inorganic compositions, while SIS selectively incorporates inorganic species into polymer matrices, maintaining compatibility with existing photoresist processes and thereby lowering industrial adoption barriers. In this mini-review, we provide a concise overview of (1) the deposition/synthesis mechanisms of MLD and SIS, (2) the interactions between various exposure sources and resist materials, and (3) the resulting photoresist performance characteristics under different lithographic conditions. Finally, we discuss future prospects of MLD- and SIS-derived hybrid resists, emphasizing their potential to overcome the intrinsic limitations of conventional organic photoresists and to emerge as practical candidates for next-generation EUV lithography.