The effect of oxygen gas pressure on Ba-ferrite sputtered films for perpendicular magnetic recording media

Abstract

Barium ferrite (BaM) sputtered films with a small c-axis dispersion angle, Delta theta /sub 50/, and smooth surface are needed for ultra-high-density perpendicular recording. These properties, which depend strongly on oxygen partial pressure, P/sub O2/, during sputtering, were studied experimentally. In the low-P/sub O2/ region (below 0.003 mTorr at total P (P/sub Ar/+P/sub O2/) of 3.7 mTorr), a spinel phase was formed and exhibited a rough surface with large grain. In the mid-P/sub O2/ (0.003-0.2 mTorr) and high-P/sub O2/ (0.3-3.7 mTorr) regions, a mixed spinel and a BaM single phase were formed, respectively. The films deposited at high P/sub O2/ exhibited large perpendicular anisotropy and consisted of needle-like particles, while those deposited at medium P/sub O2/ exhibited perpendicular anisotropy of about 1.0 kOe. The H/sub k perpendicular to / of these films was about 10 kOe, and they had a very smooth surface and small Delta theta /sub 50/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>