ARSENIC AND BORON-DIFFUSION IN SILICON FROM IMPLANTED COBALT SILICIDELAYERS

The diffusion from CoSi2 layers, implanted with As and B ions, into th e underlying Si substrate has been studied by a high-resolution carrie r delineation technique. In the early stages of diffusion the junction shape follows the silicide/silicon interface for B, while it is deepe r near the CoSi2 grain boundaries for As. The different behaviour is r elated to the different diffusion mechanisms of As and B in the silici de layer. Using a two-step anneal or a thin silicide diffusion source a laterally uniform junction has also been obtained for As-implanted C oSi2. The diffusion coefficients of arsenic and boron in silicon have been measured by this technique. The measured diffusivity values for b oron and arsenic are very close to the data reported in the literature .