MICROSTRUCTURE OF COPPER-FILMS ON SILICON WITH AN ION-BEAM-ASSISTED DEPOSITED INTERMEDIATE COPPER LAYER

Cu intermediate layers (IL) were deposited by ion beam assisted deposi tion (IBAD) on a Si(100) substrate before Cu surface films (SF) were d eposited by electron gun and their effect on the microstructure of the Cu SF was studied. The argon ion energy and current density of IBAD w ere 2-20 keV and 45 muA/cm2, respectively. The thickness of the Cu SF was 350 nm. The Cu SF, if there is no IBAD of Cu IL, have a strong pre ferential orientation of the Cu(200) plane parallel to the Si(100) sur face. The IBAD of Cu IL changes this orientation to a (111) orientatio n. For an IBAD argon ion energy of 15 keV, the Cu SF has a maximum val ue of the X-ray diffraction (XRD) peak-height ratio, i.e. I(111)/I(200 ) = 41. Scanning electron microscope (SEM) analysis shows that the Cu films with Cu IL are rougher than those without Cu IL.