Arsenic and boron diffusion in silicon from implanted cobalt silicide layers

The diffusion from CoSi2 layers, implanted with As and B ions, into the underlying Si substrate has been studied by a high-resolution carrier delineation technique. In the early stages of diffusion the junction shape follows the silicide/silicon interface for B, while it is deeper near the CoSi2 grain boundaries for As. The different behaviour is related to the different diffusion mechanisms of As and B in the silicide layer. Using a two-step anneal or a thin silicide diffusion source a laterally uniform junction has also been obtained for As-implanted CoSi2. The diffusion coefficients of arsenic and boron in silicon have been measured by this technique. The measured diffusivity values for boron and arsenic are very close to the data reported in the literature.