Enhanced Solubility of Zirconium Oxo Clusters from Diacetoxyzirconium(IV) Oxide Aqueous Solution as Inorganic Extreme‐Ultraviolet Photoresists
Sho Kataoka, Kiwamu Sue
Abstract
Abstract Metal oxo clusters have drawn a great deal of attention as the extreme‐ultraviolet (EUV) photoresists. However, industrial implementation in the next‐generation lithography demands further improvements in their sensitivity and resolution. In this study, a zirconium oxo cluster with methacrylate and acetate ligands was synthesized from diacetoxyzirconium(IV) oxide aqueous solution for use as EUV photoresist materials. The obtained Zr oxo cluster, consisting of a Zr core and methacrylate and acetate ligands, was similar in size to Zr 6 O 4 (OH) 4 (methacrylate) 12 cluster, but much more soluble in a variety of organic solvents. Open‐frame exposure tests revealed that the Zr oxo cluster served as a negative tone photoresist with a sensitivity greater than that of Zr 6 O 4 (OH) 4 (methacrylate) 12 cluster. At a dose of 22 mJ/cm 2 in the absence of photoacid generators, the Zr oxo cluster film resolved a pattern 15 nm in width, which is sufficiently low to meet the current technological requirements.