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

A new type of composite target is proposed for low Ar-gas-pressure (P
_Ar
) deposition of CoPtCr-SiO
₂
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 SiO
₂
powder. Systematic analysis of film composition, microstructure, and magnetic properties of the granular films revealed that 1) the Co
₇₄
Pt
₁₆
Cr
_10-8
mol%SiO
₂
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 SiO
₂
is important for magnetic decoupling.