HIGH-VOLTAGE ELECTRON-BEAM NANOLITHOGRAPHY ON WO3

High voltage electron beam Lithography experiments on thin films of tu ngsten trioxide are reported. For linear doses around 10 mC/cm at 200 kV, a negative resist behavior is observed after development in a NaOH solution. Features with dimensions as low as 15 nm with aspect ratios up to 10, exhibiting weak size fluctuations and vertical sidewalls ar e routinely achieved. Proximity effects are found to be negligible all owing the fabrication of structures with less than 10 nm separation. T he exposure mechanism is investigated by transmission electron microsc opy and diffraction. A crystallization process induced by the electron bombardment is clearly evidenced. A model based on the amorphous to c rystalline phase transition induced by electron irradiation is propose d to account for the experimental observations. (C) 1996 American Vacu um Society.