Heavy ion induced intermixing at Ta/Si and Ta/SiO2 interfaces

Abstract

Systematic ion beam mixing experiments have been performed on Ta/SiO2 and Ta/Si interfaces. Tantalum was evaporated on silicon and SiO2/silicon substrates by means of molecular beam epithaxy. Samples were subsequently irradiated with 500 keV Si, 100 keV C and 100 keV O ions to different ionic fluences. The irradiated samples were studied by Rutherford backscattering spectrometry (RBS) to obtain the depth profiles and the interdiffusion parameters at the interfaces. Atomic force microscopy (AFM) was used to examine the surface roughness before and after irradiation. Ballistic mixing was found in both systems. Additional contributions to diffusion parameters were thermal spike effects (Ta/Si) and chemical reactions (Ta/SiO2). Radiation enhanced diffusion was found to be the dominant process above room temperature in both systems.