Epitaxial growth of Cu films on Si by ionized cluster beam deposition

The growth of Cu films deposited by ICB method on Si(111) and Si(100) has been studied. Depositions were made in ultra high vacuum with substrates at near room temperature. The film growth was analyzed by in situ RED and XPS measurements. Channeling, x-ray diffraction, Auger spectroscopy, and scanning ion microscopy measurements were made outside the deposition chamber. The growth of Cu films on Si(111) was initially two dimensional followed above ten monolayers by the appearance of three-dimensional structures. 100 nm thick films had quite uniform crystal structure with epitaxial relation to the substrate. No intermixing or silicide formation at the interface was seen. Ion acceleration improved the smoothness of the film surface but had no appreciable effect on the film structure or interface. By contrast, in deposition on Si (100) ion acceleration strongly influenced the film structure and intermixing at the interface. Smooth films were obtained at acceleration voltage of 3 kV and higher while more disordered structure with strongly intermixed interface was observed at lower acceleration voltages. It was found that the effect of ion bombardment during film growth strongly depends on the substrate crystallographic orientation.