We propose a nanocomposite resist system that incorporates sub-nm carbon particles into a resist film to enable an ultrathin film resist process for nanometer pattern fabrication. Fullerene (C60) is found to be an excellent material for incorporation in view of its etching resistance, dissolution inhibiting effect, molecular size, and composite preparation. A nanocomposite system of C60 and an electron-beam positive resist, ZEP520, show enhancements in both pattern contrast and etching resistance and provide 50 nm patterns in a 50-nm-thick film with a sensitivity of ∼ 50 μC/cm2. Furthermore, a C60-incorporated chemically amplified resist, SAL601, shows strong environmental stabilization in postexposure delay (<10% after five days) presumably due to the reduction of free volume in the closely packed nanocomposite film. © 1997 American Institute of Physics.