X−ray investigations on CoSi2 nano wires manufactured by focused ion beam synthesis

Nanowires and chains of nanoparticles are of emerging interest in nano-electronics, nano-optics and plasmonics as well as for their monolithic integration into microelectronic devices; CoSi2 is a promising material due to its CMOS-compatibility in micro-electronics technology. It shows metallic behaviour with low resistivity and high thermal stability. It is well known that cobalt disilicide films can be formed in silicon by implanting Co in stoichiometric concentration and a subsequent annealing procedure. Ion beam synthesis allows the fabrication of epitaxial buried or surface CoSi2 layers on silicon. Sub-micron patterns with feature dimensions much smaller than 100nm can be directly produced by writing focused ion beam (FIB) cobalt implantation.
We have studied the strain of the Si host lattice in the surrounding area of a single nanostructures depending on their crystallographic orientation using high resolution x-ray diffraction in combination with a highly focused (≈ 3µm) x-ray beam at the beam line ID1 at the ESRF. The pattern measured directly on the wire shows a small peak indicating tensile strain (approx. −1.4%). This feature can be only found if the beam focused on a nano wire whereas its intensity changes
with the layer width.