XPS study of the chemical structure of the nickel/silicon interface

The chemical nature of the Ni/Si, Ni/Ni2Si, and Si/Ni2Si interfaces is studied using X-ray photoelectron spectroscopy. Two approaches are employed: (1) the Ni/silicide and Si/silicide interfaces are examined by dynamically monitoring the advancing reaction front during in situ growth and (2) as-deposited Ni/Si interfacial properties are analyzed by sequential evaporating monolayer Ni films on Si. These experiments show that the Ni/Ni2Si interface consists of a Ni-rich silicide phase, while the Si/Ni2Si interface has a transitional region that is correspondingly Si-rich silicide.