Ion Beam Mixing of Ag/Si Bilayer

Abstract

The Rutherford backscattering (RBS) technique has been used to study the ion-induced mixing of Ag thin film deposited onto Si substrates. The mixing was initiated by a 400 keV 40Ar+ beam by varying the dose up to 3 × 1017 ions/cm2 at constant flux of 0.6 μA/cm2. To assist the evaluation of the results, all spectra were simulated. The RBS spectra indicate that mixing is initiated after a dose of 5 × 1015 ions/cm2 is reached. With progressively increasing Ar dose to reach 1.6 × 1017 ions/cm2, the signal was noted to exhibit reduction of intensity accompanied by an increase of width and followed by long tail distributions, indicating a larger intermixed region. At higher doses the RBS spectra indicate that the Ag top layer was completely destroyed. The mixing rate parameters (or efficiencies) of Ag and Si were determined. Further insight into the mixing mechanism was gained by determining the diffusivities of both Ag and Si. Comparison between theory and experiment reveals that Ag diffuses within Si according to the collective effects resulting from thermal spike and thermally activated radiation enhanced diffusion (RED) mechanisms.