Metal resist for extreme ultraviolet lithography characterized by scanning transmission electron microscopy

We characterized the structures of metal resists used in EUV lithography by low-voltage aberration-corrected scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS). This study presents the first atomic-level observation of resist components in resist film. The structures of metal (zirconium or titanium) oxide cores are unambiguously identified, and the local elemental distribution in the resist film is obtained. The initial size of zirconium oxide cores is well maintained in the resist film. However, titanium oxide cores tend to aggregate to form an indefinite structure. The spatial distribution of metal cores may influence lithographic characteristics.