Diffusion and Interface Reaction of Cu/Si (100) Films Prepared by Cluster Beam Deposition

Cu thin films are deposited on Si (100) substrates by neutral cluster beams and ionized cluster beams. The atomic diffusion and interface reaction between the Cu films and the Si substrates of as-deposited and annealed at different temperatures (230°C, 450°C, 500°C and 600°C) are investigated by Rutherford backscattering spectrometry (RBS) and x-ray diffraction (XRD). Some significant results are obtained on the following aspects: (1) For the Cu/Si(100) samples prepared by neutral cluster beams and ionized cluster beams at V_a=0 kV, atomic diffusion phenomena are observed clearly in the as-deposited samples. With the increase of annealing temperature, the interdiffusion becomes more apparent. However, the diffusion intensities of the RBS spectra of the Cu/Si(100) films using neutral cluster beams are always higher than that of the Cu/Si(100) films using ionized cluster beams at V_a=0 kV in the as-deposited and samples annealed at the same temperature. The compound of Cu₃Si is observed in the as-deposited samples. (2) For the Cu/Si(100) samples prepared by ionized cluster beams at V_a=1, 3, 5 kV, atomic diffusion phenomena are observed in the as-deposited samples at V_a=1, 5 kV. For the samples prepared at V_a=3 kV, the interdiffusion phenomenon is observed until 500°C annealing temperature. The reason for the difference is discussed.