Nickel silicidation on polycrystalline silicon germanium films

The interfacial reactions of Ni with polycrystalline Si0.8Ge0.2 films at a temperature range of 300-900degreesC by rapid thermal annealing for 60s are studied. The sheet resistances of the silicide films were relatively low at similar to10 ohm/sq for samples annealed below 600degreesC. X-Ray diffraction results suggested the existence of low resistivity phase Ni(Si1-xGex) in the film. The significant increase in sheet resistance for films annealed at 700-900degreesC is probably due to the reduction in the density of Ni(Si1-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(Si1-xGex) on polycrystalline Si1-xGex films. Rutherford backscattering results showed that for films annealed at a temperature range of 300-600degreesC, Ni has reacted with the polycrystalline films. However, at an annealing temperature higher than 700degreesC, Ni diffused through the whole film.