High Resolution Delineation of Bi-dimensional Dopant Profiles in Silicon: Early Stages of Diffusion from Cobalt Silicide Layers

The early stages of diffusion into crystalline Si from 170 nm thick CoSi₂ layers doped with As and B have been studied by a high resolution delineation technique of dopant profiles. The junction shape follows the silicide-silicon interface for B while it is deeper near the grain boundary for As. The different behaviour is related to the different diffusion mechanisms of As and B in the silicide layer. The junction shape has a great effect on the reverse characteristics of the diodes obtained by As or B diffusion from the CoSi₂ layer.