Distributions of hafnia and titania cores in EUV metal resists evaluated by scanning transmission electron microscopy and electron energy loss spectroscopy

Abstract

The morphologies of hafnia (HfOx) and titania (TiOx) cores and their distributions in metal resists for EUV lithography were characterized at the atomic level by scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). The HfOx cores show a higher affinity to organic components, such as methacrylic acid and benzoic acid, than the TiOx cores, and the same core–shell state as in a solution is almost completely maintained in the HfOx resist film. Furthermore, it was found that the surface modification of the TiOx cores by silylation is effective for preventing their aggregation and improves the postcoating delay (PCD) of the resist.