NiSi2 formation through annealing of nickel and dysprosium stack on Si(100) and impact on effective Schottky barrier height

Abstract

Rapid thermal annealing of nickel-dysprosium (Ni-Dy) film stacks on silicon (Si) was investigated, and formation of the nickel disilicide (NiSi2) phase was observed. The formation mechanism for the NiSi2 phase was elucidated. The nucleation, growth, and distribution of the inverted NiSi2 pyramids can be explained from both the thermodynamic and kinetic aspects of the solid-state reaction. In addition, lowering of the effective electron Schottky barrier height (ΦBn,eff) of NiSi2 on Si was observed. The high electric field at the tips of the inverted NiSi2 pyramids increases the tunneling probability of electrons, and results in thermionic field emission being the dominant carrier transport mechanism at the NiSi2/Si interface. This contributes significantly to an increase in reverse bias current and gives a reduced ΦBn,eff. An analytical expression for the localized electric field is derived and it is found to be as high as ∼1.9 × 106 V/cm based on our experimental result.