Tailoring of epitaxial CoSi₂/Si nanostructures by low temperature wet oxidation

We have investigated a process for tailoring of epitaxial CoSi ₂/Si nanostructures using low temperature wet oxidation. A separation between two CoSi₂ layers on a Si substrate in the range of 60 nm is generated by a self-assembly process. During subsequent low temperature wet oxidation, SiO₂ formation on top of the silicide layers pushes the latter into the substrate. At the edges of the gap, the silicide layers are shifted in both and directions, leading to an effective reduction of the separation width to dimensions below 20 nm and eventually to merging of the two layers. The significantly lower oxidation rate of the silicon in the initial gap compared with the CoSi₂ provides the excess Si for the shift in the direction. The structures were investigated using transmission electron microscopy (TEM) and scanning electron microscopy (SEM).