Arsenic clustering during formation of the transient Ni silicide

The redistribution of arsenic during the reaction of Ni thin films with arsenic-doped Si(1 0 0) substrates is studied by in situ X-ray diffraction (XRD) and atom probe tomography. In situ XRD showed the formation of a transient phase that forms isolated grains at the δ-Ni2Si/Si interface. Arsenic is not incorporated in δ-Ni2Si but accumulates at the δ-Ni2Si/Si interface. Clusters containing 10 at.% As are present only in the transient phase. The As clustering might have important consequences for devices.