Ion mixing in Ag-films on Si-substrates induced by a high fluence ⁴⁰Ar⁺ beam with a flux of 0.2 μA/cm²

Characteristics of ion mixing in thin Ag-films deposited onto Si-substrates were studied using the Rutherford backscattering (RBS) technique. The mixing was induced by a 400 keV ⁴⁰Ar⁺ beam with a flux of 0.2 μA/cm² and fluences of up to 4 × 10¹⁷ ions/cm². The concentration of Ag and Si atoms and their distributions in depth within the mixed region were determined. The RBS data indicate a clear broadening of the interfacial edges of Ag and Si distributions caused by atomic intermixing of the interface for doses above 7 × 10¹⁶ ions/cm². The size of the intermixed region increases with increasing Ar fluence. Experimental findings also indicated that radiation-enhanced diffusion had not been totally eliminated. The mixing efficiency and diffusivity of Si and Ag were determined. Theoretical models were used to describe the mixing process. A comparison of our data with theory revealed that Ag diffuses in Si according to a local 'thermal spike' model. The above results when compared with our earlier studies of the Ag/Si system at a flux of 0.6 μA/cm² under otherwise similar conditions indicate that the mixing in this system is flux dependent.