Influences of sputtering gas pressure on microtexture and crystallographic characteristics of Ba-ferrite thin films for high density recording media

Ba-ferrite films with small c-axis dispersion angle Δθ
50
are suitable for ultrahigh density recording media. The dependences of partial oxygen gas pressure P
O2
and total discharge gas pressure P
Total
on the characteristics of Ba-ferrite films were clarified. It was found that there were three regions, where films were composed of single layer of spinel type ferrite(P
O2
≤0.002mTorr), mixed layer of spinel and magnetoplumbite type ferrites (
0.003 \leq P_{O2} \leq 0.2
mTorr) and single layer of magnetoplumbite type ferrite (P
O2
>0.3 mTorr). In the range of P
02
between 0.005 and 0.2 mTorr, spinel-like ferrite layer plays very important role as an underlayer to decrease the Δθ
50
of the Ba-ferrite layer. Films deposited at relatively low P
O2
and P
Total
exhibit very smooth surface and Δθ
50
as small as
2.5\sim3.5\deg
.