Epitaxial growth of Cu thin films on atomically cleaned (111)Si at room temperature

Abstract

Epitaxial Cu thin films have been grown on (111)Si at room temperature in an ultrahigh vacuum environment. Plan-view and cross-sectional transmission electron microscopy revealed that both aligned and twinned epitaxy were present. An interface compound, about ten atomic layers in thickness, was observed to be present at the Cu Si interface. From atomic image and diffraction analysis, the intermediate layer was identified as ζ phase, which is of h.c.p. CuSi x structure with x = 11.2−14 at.%. Interfacial dislocations at the silicide/Si interface were identified as edge type, with 1 2 〈11̄0〉 Burger's vectors. The average spacing of the dislocations was measured to be 1.4 nm, which correlates well with a 15% mismatch at the silicide/Si interface.