Terbium iron cobalt diffusion barrier studies

Abstract

Thin films (5nm ± 2nm thick) of ZrO2, Al2O3, TiO2, Sm, Gd, Zr, Ni, and Pt were deposited onto TbFeCo films (100nm ± 20nm thick) on silicon and graphite substrates and analyzed with XPS as prospective candidates for TbFeCo diffusion barriers. Metals were chosen primarily according to electronegativity. Samples were typically heated to 272°C in UHV for 20 hours to enhance diffusion. Experiments with the metals were performed in a more consistent manner than with the oxides. The Sm, Gd, and Zr were reactively oxidized during the deposition. The Sm/Sm-oxide and Gd/Gd-oxide appeared to be favorable candidates for TbFeCo diffusion barriers. TbFeCo was not detected near the surface before or after heating the samples to 272°C for 20 hours and depth profiles indicated oxygen contamination decreased steadily as the barrier/TbFeCo interface was approached. For the other materials examined, either the oxides were reduced (at least partially) during heating to 272°C (381°C for Al₂O₃) or diffusion of TbFeCo was detected after heating, indicating that they would not be favorable candidates for TbFeCo diffusion barriers.