Silicide Formation during Heat Treatment of Thin Ni-Pt and Ni-Pd Solid-Solution Films and Pt/Ni Bilayers on (111)Si

摘要

It is shown that isothermal heat treatment of (Ni-Pt)/Si and Pt/Ni/Si heterostructures leads to the formation of oriented Ni- and Pt-based silicide solid solutions. Owing to the three equivalent azimuth orientations in the basic lattice orientation relationship for the Si—Ni_(1-x)Pt_xSi system, the resulting silicides have a nanocrystalline substructure. The stability of the substructure is due to the optimal interfacial lattice match and near-special grain-boundary misorientations. The silicide phases Ni_(1-x)Pt_xSi and Pt_(1-y)Ni_ySi (or Ni_(1-x)Pd_xSi and Pd_(1-y)Ni_ySi) may undergo segregation, having the same lattice orientation. In both systems, the segregation is associated with the predominant Ni diffusion. The second component (Pt) is shown to stabilize the orthorhom-bic Ni-based silicide and to prevent NiSi_2 formation. Photon processing accelerates diffusion and leads to the formation of phase-pure Ni_(1-x)Pt_xSi solid solutions.