A New Technique to Produce Single Crystal Epitaxial Nano-Structures.

High dose ion implantation into silicon followed by annealing can lead to the formation of buried stoichiometric silicide layers for a variety of implanted species. Of particular interest here is the implantation of cobalt ions. It has been shown that with an implant dose of ~2x10 sup (17) cm sup (-2) and an anneal temperature of the order 1000C a single-crystal oriented layer of metallic cobalt disilicide is formed within the bulk silicon. This technique is known as mesotaxy [1]. The process is illustrated in figure 1 by reference to Rutherford Backscattering Spectroscopy (RBS) of the material both post- implant (fig. 1a) and post-anneal (fig. 1b). The as-implanted cobalt distribution as a function of depth is the usual skewed Gaussian and shows some degree of crystalline order. However, after annealing the profile shows a dramatic sharpening and increase in crystallinity. Furthermore, transmission electron microscopy (TEM) reveals that the silicide layer and the silicon are uni-axial and the interfaces are abrupt and relatively smooth.