Deposition of c-axis oriented Ba ferrite thin films by atomic layer deposition method for high density magnetic recording media

Abstract

In this study, c-axis oriented Ba-ferrite (BaM:BaFe12O19) films about thick 115 nm thick were deposited using an alternate atomic layer deposition method. R layer (BaO·3Fe2O3 layer) thicknesses from 4.6 to 5.9 A and S layer (spinel: Fe3O4 layer) thicknesses from 4.6 to 5.4 A deposited 100 times alternately by sputtering at a substrate temperature between 580 °C and 655 °C in an atmosphere of 90%Ar and 10%O2. Before the BaM films were deposited, a ZnO underlayer 15 nm thick was deposited on the thermally oxidized silicon wafer substrate. A strict control of the thickness of R layer and S layer was necessary to obtain a single hexagonal BaM phase. A single-phase BaM film obtained by alternate deposition of 6.9 A R layers and 4.6 A S layers at 630 °C had excellent c-axis orientation ( Δθ50 = 2.4° ). Typical magnetic properties of the film were as follows: saturation magnetization Ms=200 emu/cc, perpendicular coercivity Hc⊥ = 3.1 kOe and in-plane coercivity Hc//=0.17 kOe.