Co–Pt–Cr–CoSi–CoO Sintered Target for Low Ar-gas-pressure Deposition of ${\hbox {CoPtCr-SiO}}_{2}$ Granular Film with Stoichiometric

A new type of composite target is proposed for low Ar-gas-pressure (P_Ar) deposition of CoPtCr-SiO₂ granular perpendicular magnetic recording media. The proposed target is a Co-Pt-Cr-CoSi-enriched CoO sintered target, consisting of CoSi and CoO powders instead of SiO₂ powder. Systematic analysis of film composition, microstructure, and magnetic properties of the granular films revealed that 1) the Co₇₄Pt₁₆Cr_10-8 mol%SiO₂ granular film with O/Si ratio of 2 in the film is realized by using a CoO/CoSi ratio of 3 in the target for our sputtering system, and 2) media with S=1, H_c=5.0 kOe, and α = 2.9 was realized even under a low P_Ar of 0.6 Pa. This means that just the oxidization of Si into SiO₂ is important for magnetic decoupling.