Focused Ion Beam vs Focused Electron Beam Deposition of Cobalt Silicide Nanostructures Using Single-Source Precursors: Implications for Nanoelectronic Gates, Interconnects, and Spintronics

Direct-write techniques for the fabrication of nanostructures are of specific interest due to their ability for a maskless fabrication of any arbitrary three-dimensional shape. To date, there is a very limited number of reports describing differences in the focused ion and electron beam induced deposition (FIBID/FEBID) for the same precursor species. This report contributes to filling this gap by testing two single-source precursors for the deposition of cobalt silicide in Ga-ion beam writing and reveals H₂Si(Co(CO)₄)₂to be a very suitable precursor for the technique retaining the 2:1 ratio of Co:Si in the deposit. Maximum metal/metalloid contents of up to 90 atom % are obtained in FIBID deposits, while FEBID with the same precursor provides material containing <60 atom % total metal/metalloid content. A dense deposit is obtained by using FEBID showing paramagnetic behavior and electric properties of a granular metal. In contrast, the FIBID material is porous and the expected ferromagnetic and temperature-dependent electric properties for dicobalt silicide have been observed. Further analysis enabled the proposition of different dominating material conversion channels based on the observed microstructural features including bubble formation in FIBID-derived material. The differences in materials properties depending on the deposition strategy can influence the cobalt silicide deposits' applicability in nanoelectronics and spintronics.