Fabrication of thin buried CoSi 2 layers in Si(100) by ion beam synthesis

Abstract

Si/CoSi 2/Si heterostructures were fabricated by 40 keV Co + ion implantation in Si(100) and subsequent annealing. In order to improve the uniformity and crystallinity of thin buries silicide layers, we studied the influence of the implantation parameters by varying the implantation temperature and the beam current density systematically over a wide range. Rutherford backscattering spectroscopy, ion channeling, cross-section transmission electron microscopy and resistivity measurements were used to correlate the experimental parameters with the morphology of the buried layer. The experiments showed that the substrate temperature during implantation and the beam current density are strongly correlated in their effect on the layer morphology. The optimal beam current density increases with increasing implantation temperature. Using optimal implantation parameters, single-crystal, continuous CoSi 2 layers buried within Si(100) with uniform thicknesses as small as 25 nm and specific electric resistivities of 1.9 microOhms cm at 4.2 K and 14.5 microOhms cm at 300 K could be fabricated.