Etchant‐Free Dry‐Developable Extreme Ultraviolet Photoresist Materials Utilizing N‐Heterocyclic Carbene–Metal Complexes

Extreme ultraviolet (EUV) lithography has enabled significant reductions in device dimensions but is often limited by capillary force‐driven pattern collapse in conventional wet processes. Recent dry‐development approaches, while promising, frequently require toxic etchants or specialized equipment, limiting their broader applicability and highlighting the need for more sustainable, cost‐effective alternatives. In this study, highly reactive, etchant‐free dry‐developable EUV photoresists using N‐heterocyclic carbene (NHC)‐based metal‐ligand complexes, achieving half‐saturation at EUV doses of 8.5 or 27 mJ cm −2 , are synthesized. A simple thermal dry development process is employed, utilizing a standard furnace to remove unexposed areas of the photoresist, leading to 80 nm resolution with line‐edge roughness (LER) comparable to wet‐developed patterns. Moreover, EUV‐induced chemical reactions of the NHC metal‐ligand complexes are investigated via EUV‐photoelectron spectroscopy, near‐edge X‐ray absorption fine structures, X‐ray photoelectron spectroscopy, and density functional theory. It is suggested that the high EUV sensitivity of the NHC metal‐ligand complexes is attributed to branching polymerization reactions initiated by secondary electron and photoelectron generation. These EUV‐sensitive, dry‐developable NHC metal–organic photoresists offer a sustainable and economical alternative to conventional techniques, eliminating the need for toxic and corrosive etchants while achieving high‐resolution nanopatterns through simple thermal treatment, thus advancing future nanofabrication technologies.