Influence of ion implantation induced defects on formation of buried CoSi2 structures in Si(100)

The evolution of buried structures of cobalt disilicide formed in a Si(1 0 0) matrix by 400 keV Co+ implantation at 875 K substrate temperature was studied by cross-sectional transmission electron microscopy. Varying the dose of implanted ions allowed a detailed study of the role of defects created by the Co+ flux in nucleation and growth Of CoSi2 precipitates. Implantation induced defects create diffusive links that assist in anisotropic diffusion of Co in the bulk resulting in organized self-growth of long rectangular precipitates with alignment along the <1 1 1> direction toward the surface. The transport of the implanted material along these diffusive links eventually leads to the formation of a second CoSi2 band between the main layer and the surface. This mechanism is considered to be the reason for the formation of several buried layers of disilicide. (C) 2002 Elsevier Science B.V. All rights reserved.