Cu-Ni and Ni-Cu bilayers on silicon: reduction of formation temperature and phase separation

Abstract

The solid state reaction between Ni-Cu and Cu-Ni bilayers on Si(100) has been studied using X-ray diffraction, transmission electron microscopy, Auger electron spectroscopy and sheet resistance measurements. The bilayers were produced by evaporation and annealed at temperatures between 200 and 500 °C. In the Ni-Cu sequence, a strong intermixing of silicides and a 33% reduction in the formation temperature of the NiSi2 phase compared with Ni-Si(100) was observed. When nickel was in direct contact with the silicon substrate limited intermixing and reaction of Cu was observed in the Cu-NiSi and NiSi-Si interfaces at 500 °C, due to the large grain size of the nickel silicide.