Effects of sputtering conditions on the recording characteristics of iron oxide thin film media

Abstract

Sputtered y-Fe2O3thin film media have received considerable attention due to its low media noise characteristics as compared with thin metallic alloy films. In this paper, the film preparation conditions, structure analysis as well as media noise and other recording characteristics are studied. Magnetite films (Fe3O4) were reactively sputtered onto (100) silicon substrates in an Ar + O2gas environment from a target containing Fe and 0.75 at. % Os. The films were further oxidized in air to form y-Fe2O3. The oxide thin film disks were then written with a thin film inductive head and read back with an experimental shielded MR element for recording performance evaluation. The media noise increases with written transition density and reaches a plateau at a linear density greater than 2000 flux changes per millimeter (fcmm). This media noise plateau as well as the noise per transition at lower density were found to increase with deposition substrate temperature, but decrease with oxygen flow rate. The structural analysis of these films further indicates that the media noise improvement is a result of grain size reduction, consistent with earlier observations2, 3However, films deposited at lower substrate temperatures exhibit degradation in B.H loop squareness resulting in poor overwrite, peak jitter, peak shift and -3 dB density. Coupled with our previously reported results,7, 8the optimized media based on both magnetic and mechanical properties is formed by depositing at a substrate temperature above 200°C and at an appropriate oxygen partial pressure. © 1988 IEEE