Surface roughness of molecular resist for EUV lithography

Surface roughness of molecular and polymer resists were probed with an atomic force microscope (AFM) and analyzed using the power spectrum density (PSD) function. The PSD curve obtained from AFM image of the molecular resist showed a broad profile dependent on the exposure dose and small roughness. The PSD increased more in the low spatial frequency range after the exposure and the correlation length was increased. Meanwhile, the PSD of the polymer resist showed a narrow profile with respect to the dose and large roughness. Overall increase in PSD with respect to the spatial frequency was observed after the exposure.

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