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.

Ion beam mixing of silicon-germanium thin films

“…27 In addition to the above methods, the novel technique of ion beam mixing (IM) by which nonequilibrium or metastable alloys and intermetallic compounds on surfaces can be formed is of value. The rapid development in materials science and technology based on the surface and near-surface properties of materials and their modifications under ion beam irradiation [28][29][30] has gained much attention in a wide variety of scientific and industrial fields (for example, the references in Reference 29). Important applications can be cited and include the adhesion between two (or multi-) layers, the preparation of junctions and electrical contacts, and the low cost layer deposition by IM to give requisite interface bond strengths.…”

“…Ballistic collisions, defect production, migration (whether chemically guided or chemically not guided), radiation-enhanced diffusion (RED), and other phenomena are, however, initiated when thin films are bombarded by energetic heavy ions. [28][29][30][31][32][33] Subsequently, changes in the spatial distribution of the elemental species accompanied by the formation of defects take place as a result of collisional cascades intersecting the interface and produce intimate mixing between the layers. Limitations in the maximum energy of the bombarding ions will limit the thickness of the active device.…”