Effect of organic ligand and metal nano-cluster core structure on resist performance of inorganic-organic hybrid resist materials for EUV lithography

In the realization of further miniaturization of patterning feature sizes less than 10 nm in semiconductor devices, it is essential to get the new resist design strategy such as inorganic-organic hybrid resist materials for ionizing radiation to clarify the effect of organic ligand and metal nanocluster core structure on resist performances. In this study, the inorganic-organic hybrid resist materials known as metal-oxo clusters with four kinds of organic ligands and three kinds of metal nanocluster core were synthesized and their resist performances such as resolution and sensitivity were examined upon exposed to EUV and EB. We successfully synthesized inorganic-organic resist materials with tiglic acid and angelic acid, which are used as new organic ligands and examined their resist performance. Our results indicated that the sensitivity in metal oxo clusters with tiglic acid was higher than those of metal oxo clusters with other organic ligands in EB. Although the exposure dose was not optimized, the patterns of Hf-and Zr-based oxo clusters with four kind of ligands showed 50 nm line and space patterns while 100 nm line and space patterns were obtained in Ti-base oxo clusters. We clarified the sensitivity of metal oxo clusters with aromatic carboxylate ligands was lower than that of metal oxo clusters with unsaturated aliphatic carboxylate ligands. Metal oxo clusters resists have the potential as future negative tone resist materials for EUV lithography.