Pd Migration in Tetragonal-Ni_(1-x)Pd_xSi/Si(001) Using Density Functional Theory

摘要

Pd migration in tetragonal-Ni_(1-x)Pd_xSi/Si (001) structure was studied to understand the mechanism of Pd segregation at the interface by using density functional theory (DFT). A plane with Ni atoms was chosen as the terminating interface layer of the tetragonal-NiSi for the tetragonal-Ni_(1-x)Pd_xSi/Si (001). Two different Ni sites were indentified at the interface, and the Ni sites farther away from the Si substrate were more favorable for Pd substitution. Ni vacancies were produced at the interface Ni sites, and the energy barrier for Pd migration from a bulk Ni site to an interface Ni site was calculated to be 4.56 eV. Pd segregation at the interface, therefore, was not through this migration path during the heat treatment of silicidation, as the energy barrier was rather high to be overcome.