Contrast Enhancement of ZEP520 Resist by Fullerene-Derivative Incorporation

A fullerene-derivative nanocomposite resist system based on a positive-type electron-beam resist, ZEP520, is examined for contrast enhancement. The system containing 10 wt% of the derivative shows a substantially enhanced γ-value of 22.9, which is about three-and-a-half times higher than that of a virgin ZEP resist, and exhibits a very-high-contrast 50 nm pattern in an ultrathin film of 150 nm. Etching resistance is also enhanced and the derivative seems to be as effective as C 60 in terms of the number of molecules incorporated. The contrast enhancement by fullerene-derivative incorporation has the potential to further improve the resolution of ZEP and will extend its application in nanolithography.