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 sy stem containing 10 wt% of the derivative shows a substantially enhanced gam ma -value of 22.9, which is about three-and-a-half times higher than that o f a virgin ZEP resist. and exhibits a very-high-contrast 50 nm pattern in a n ultrathin film of 150 nm. Etching resistance is also enhanced and the der ivative seems to be as effective as C-60 in terms of the number of molecule s incorporated. The contrast enhancement by fullerene-derivative incorporat ion has the potential to further improve the resolution of ZEP and will ext end its application in nanolithography.