Nickel silicidation on polycrystalline silicon germanium films

Abstract

The interfacial reactions of Ni with polycrystalline Si0.8Ge0.2 films at a temperature range of 300-900°C by rapid thermal annealing for 60s are studied. The sheet resistances of the silicide films were relatively low at ∼ 10 ohm/sq for samples annealed below 600°C. X-Ray diffraction results suggested the existence of low resistivity phase Ni(Sil.xGex) in the film. The significant increase in sheet resistance for films annealed at 700-900°C is probably due to the reduction in the density of Ni(Sil.xGex) as a result of fast Ni diffusion at high annealing temperatures. Fast grain boundary diffusion of Ni was suggested to cause the lowering of formation temperature of Ni(Sil.xGex) on polycrystalline Sil.xGex films. Rutherford backscattering results showed that for films annealed at a temperature range of 300-600°C, Ni has reacted with the polycrystalline films. However, at an annealing temperature higher than 700°C, Ni diffused through the whole film.