EPITAXIAL-GROWTH OF CU THIN-FILMS ON ATOMICALLY CLEANED (111)SI AT ROOM-TEMPERATURE

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 zeta phase, which is of h.c.p. CuSix structure with x=11.2-14 at.%. Interfacial dislocations at the silicide/Si interface were identified as edge type, with 1/2(1 $($) over bar$$ 10) 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.