Inhomogeneity of PAGs in a hybrid-type EUV resist system studied by molecular-dynamics simulations for EUV lithography

It is desirable to simultaneously improve the resolution, line-edge roughness (LER), and sensitivity of extreme ultraviolet (EUV) resist materials. In a resist film, nanometer-scale inhomogeneous structures may have significant direct effects on the resolution and LER along with indirect effects on sensitivity. This study will evaluate the inhomogeneity of photoacid generators (PAGs) in a hybrid-type EUV resist film using molecular-dynamics simulations. The results show the inhomogeneity of PAG positions and motions in the resist film. Moreover, PAG anions show larger diffusion coefficients than PAG cations. These results can be elucidated in terms of the free volumes in the resist matrix and the molecular structures of PAG, such as the bulky phenyl groups of PAG cations and the fluorine-atom interactions in PAG anions.