Published online by Cambridge University Press: 15 February 2011
The formation and the relaxation of NiSi2 films with and without Au are examined by scanning electron microscopy, X-ray diffraction and Rutherford backscattering spectrometry. We studied the solid state reactions between a Ni(7 at.% Au) thin film and a Si substrate which occurs during the solid phase epitaxy before the formation of NiSi2. We show that the addition of Au to the Ni film drastically affects the silicides formation: Ni2Si and NiSi appear simultaneously and the nucleation temperature of NiSi 2 is lowered. The solubility of Au in the three silicides is limited which induces a precipitation of Au. Depending on temperature this precipitation takes various forms: Au enriched surface layer or Au clusters at inner interfaces. The films lattice parameters both parallel and perpendicular to the interface are also measured and compared to the lattice parameters of bulk samples which have been made by solidification from the melt. The relaxation modes are deduced from these measurements.