In developing high sensitivity extreme ultraviolet (EUV) resists, we focused on the fact that EUV photon absorption by
chalcogen atoms is larger than that by carbon or hydrogen atoms. We chose this focus because it is considered that in
EUV the absorption of incident radiation by base polymers influences acid generation. To determine the effects of
introducing chalcogen atoms into base polymers under EUV exposure on lithography performance, we synthesized novel
co-polymers of novel methacylate monomers that included oxygen and sulfur atoms in acid-cleavable moiety as well as
polar monomers, and evaluated their sensitivity under EUV and ArF exposure. The sensitivity of polymers that were rich
in chalcogen atom content improved more under EUV exposure than under ArF exposure. We also used a highsensitivity
quadrupole mass spectrometer (QMS) to observe the outgassing species generated from these polymers under
EUV exposure in detail.
We synthesized several new monomers with an acid-cleavable protective group and investigated their deprotection
reactions. Polymers were prepared using these monomers, and their thermal properties and dissolution rates were
investigated. The acidic reactivity of protective groups of these monomers was evaluated using a method we developed.
The activation energies [<i>E</i><sub>a</sub>(experimental)] calculated using reaction rate constants were found to correlate to some extent
with the activation energies [<i>E</i><sub>a</sub>(calculated)] calculated from MOPAC. The dissolution rates of some polymers containing
similar protective groups as structures were measured. The dissolution rates were related to the polarity and molecular
volume (MV) of the decomposed products of protective groups.