Thermal Stability of Metal Films Deposited by Ionized Cluster Beams

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Abstract
Our previous experiments have shown that Al and Au films deposited on Si substrates by ionized cluster beams (ICB) exhibit high thermal stability and .long electromigration life time. To understand these characteristics, in-situ XPS measurements during ICB deposition of Au on Si(111) substrate have been made. The results show that at low coverages, the splitting between the two prominent structures in the Au-5d peaks in the valence band becomes closer to those of pure bulk gold when a film is deposited at high acceleration voltages. In contrast to this an appreciable change of the binding energy of the Si-2p state at low coverage and high acceleration voltage could not be observed. These results suggest that a high density layer is formed and any Au-Si interaction is suppressed at the initial stage of film deposition. This could be one of the reasons why ICB-deposited films exhibit high thermal stability.