Tailoring of epitaxial CoSi_2/Si nanostructures by low temperature wet oxidation

摘要

We have investigated a process for tailoring of epitaxial CoSi_2/Si nanostructures using low temperature wet oxidation. A separation between two CoSi_2 layers on a Si substrate in the range of 60 nm is generated by a self-assembly process. During subsequent low temperature wet oxidation. SiO_2 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 (100) and (111) 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 CoSi_2 provides the excess Si for the shift in the (111) direction. The structures were investigated using transmission electron microscopy (TEM) and scanning electron microscopy (SEM).