REACTIONS AT THE ALUMINUM-OXIDE FERRITE INTERFACE

Sputter-deposited aluminum oxide films on Ni-Zn ferrite substrates are used as passivation and insulation layers in fabricating magnetic recording devices. Auger electron spectroscopy and X-ray photoelectron spectroscopy have been used to monitor the changes in the Al2O3 target after being ion sputtered and the chemical reactions that take place between the deposited aluminum oxide and the ferrite substrate. Sputtering of Al2O3 target with pure argon preferentially removed some oxygen and, as a result, an oxygen-deficient aluminum oxide was formed on the target surface. During the initial aluminum oxide film growth on the ferrite surface, the sputtered species tended to satisfy its oxygen-deficient state by "stealing" oxygen from the neighboring environment. The reactions, therefore, resulted in the formation of a metallic iron phase on the ferrite surface, making the surface electrically conductive. Sputtering of the Al2O3 target with argon gas having an oxygen content of approximately 0.1% allowed the sputtered species to react with oxygen either in space or on the ferrite surface. This mechanism created a less reducing environment which did not allow metallic iron phase formation on the ferrite surface and thus the surface remained electrically non-conductive.