Electron beam-induced organometallic chemical vapor deposition for nanostructure fabrication

Abstract

I show that nanometer scale metal-containing features can be fabricated in selected areas using noncarbonyl organometallics and a focused electron beam. Nanostructures are fabricated by electron beam-induced organometallic chemical vapor deposition from precursors ferrocene and nickelocene using a field emission scanning transmission electron microscope (STEM). Lines of 4 nm wide with uniform width and smooth surface are routinely obtained using a focused electron beam with probe size near 1nm. In-situ investigation for the effects of deposition conditions on the mechanism of film growth has been conducted in the STEM. Substrate temperature and organometallic partial pressure play an important role in the growth mechanism. Two different film growth mechanisms and two resulting structures of the deposited material are found at different deposition conditions. The ratio of organometallic partial pressure during deposition (P_OM) to its equilibrium vapor pressure (P_v) at the corresponding substrate temperature is found to be a governing parameter for the film growth mechanism and hence the structure of deposition results. Either uniform deposits with high edge acuity or 3-dimensional nano-network structure can be obtained by selecting a suitable combination of organometallic partial pressure and substrate temperature. The effects of deposition conditions such as electron dose, hydrogen additive and low temperature annealing after deposition on the deposition results have also been addressed.