Behaviour of copper atoms in annealed CurSiO rSi systems

Copper thin films of thickness 1000 A° are evaporated on 100.and 111.single crystal Si wafers in the presence of interfacial native silicon oxide SiO.. The behavior of copper and the mechanism of compound formation at the CurSi x interface are studied at different temperatures using scanning electron microscopy SEM., X-ray diffraction XRD.and Rutherford backscattering RBS.. Annealing in the 600–7508C temperature range leads to the formation of islands of two copper-rich silicides Cu3Si and Cu4Si. On the Si 100., after annealing at 7508C, we observe epitaxially grown Cu3Si crystallites with square and rectangular shapes. However, on Si 111.annealing at the same temperature yields Cu3Si and Cu4Si crystallites with droplet-like shapes and no sign of epitaxy. The presence of oxygen, after heat treatment under vacuum, is closely related to the formation of copper silicide crystallites. q2000 Elsevier Science B.V. All rights reserved.