Quantitative determination of the dopant distribution in Si ultra shallow junctions by tilted sample annular dark field scanning transmission electron microscopy

In this letter, it is shown how the application of a Z-contrast scanning transmission electron microscopy technique to the study of the dopant signal in ultrashallow junctions in Si can lead, in the case of As in Si, to a quantitative determination of the dopant depth profile at subnanometer resolution. The quantitative results thus obtained demonstrate that As accumulates on the Si side of the SiO2/Si interface with a negligible loss of dopant into the oxide. Modeling of the effect indicates that segregation occurring during the recrystallization of the implanted layer is the dominant cause of this dopant pileup.