Analysis of Cu Silicides by Atom-probe Field Ion Microscope

Phase formation and diffusion have been investigated in Cu-Si system. Field ion microscope (FIM) and atom-probe field ion microscope (AP-FIM) were used to determine the crystal structures and chemical compositions of the grown phases. From the results of depth profile by AP-FIM, it is proved that the silicide phase take the layer structure of Cu-Si mixture layer and pure Cu layer. The Cu silicide phase estimated was Cu3Si of orthorhombic structure. The orientation relationship of silicide and Si substrate was [111]Cu3Si || [111]Si. The measured value of the diffusion of Cu atoms in Si was four orders in magnitude smaller than the estimated value calculated by the equation of Hall and Racette. Field ion images of Cu atoms in the Cu silicides were dark compared with Si atoms, so that the crystal structures of the Cu silicides have not been determined by FIM.