A vapor-phase dry development process utilizing the β-diketone compound hexafluoroacetylacetone (hfacH) was applied to a nanoscale zinc-based metal–organic photoresist (ZnOR) with a vertically aligned molecular wire architecture. X-ray photoelectron spectroscopy (XPS) confirmed that exposure-induced Zn–O–Zn and Zn–S–Zn coordination networks remained intact during vapor-phase dry development, while unexposed regions underwent rapid Zn removal via β-diketone chelation. The development is governed by a surface-reaction-limited mechanism that suppresses developer penetration and resists swelling, in contrast to conventional wet development. Although the vapor-phase process exhibits a development contrast (γ = 1.18) lower than that of wet development (γ = 1.77), it achieves superior dimensional control in terms of pattern-to-pattern critical dimension (CD) variability at the nanoscale. Under identical exposure conditions, vapor-phase dry development enabled stable line-and-space patterning down to a 14 nm critical dimension with a development selectivity of 5.8. Pattern-to-pattern CD uniformity was significantly improved, yielding 3σ = 2.07 nm for 50 nm half-pitch square arrays, corresponding to an approximately 35% reduction in CD variation compared to conventional wet development. These results suggest that CD uniformity of nanoscale features is governed not solely by development contrast but by the stability of the reaction front during development, establishing β-diketone-mediated vapor-phase dry development as a robust strategy for reliable dimensional control in terms of pattern-to-pattern CD variability in Zn-based metal–organic EUV photoresists.
Seok et al. (Fri,) studied this question.