FIB assisted silicide nanowires formation in silicon

Focused Ion Beam (FIB) is one of the most suitable tools for sub-µm structure fabrication, modification and investigation. Combining FIB and self organization processes during ion beam synthesis a reduction of the FIB written structures can be provided. The Rossendorf FIB system allows the operation with a Ga liquid metal ion source (LMIS) as well as with a CoNd alloy LMIS. Formation of CoSi2 nanoparticles and nanowires in silicon was investigated using Co++ ions from the CoNd LMIS. Si(111) and Si(100) samples were implanted with a fine focused cobalt ion beam at elevated sample temperatures as well as at room temperature. Subsequent annealing steps lead to the formation crystalline CoSi2 long nanowires with diameter down to 10-20 nm in the crystalline substrate. These structures were analyzed using SEM and AFM. Two main mechanisms of the nanowires formation have been observed: via coalescence of the implanted Co nanoparticles with following Oswald ripening and via diffusion of Co atoms during annealing into “linear defects” induced by FIB irradiation. Further efforts are concentrated in increasing of reproducibility of nanowire growth and then the fabrication of nanodevices.