Effect of Ar-gas-pressure on oxygen content of Co-Si-O granular film sputter-deposited by using sintered targets

A systematic study of the effect of Ar-gas-pressure (P_Ar) in Co-Si-O granular film by sputter deposition using sintered targets is carried out for applications in CoPtCr-SiO₂ perpendicular media. Detailed analyses of composition, phase formation and microstructure of granular films revealed that: (1) Co-Si-O granular films with similar compositions could be prepared by different sintered targets, (Co)+(SiO₂), (Co)+(CoSi)+(CoO), (Co)+(Si)+(CoO), and (Co)+(Si)+(Co₃O₄), (2) oxygen content in film increases with increasing P_Ar, (3) oxygen content in film could be adjustable by the target composition (e.g. (CoO)/(CoSi)). Taking these results into account, we tried low P_Ar deposition of Co-Si-O granular film. Under P_Ar 0.6 Pa, oxygen-poor Co-Si-O granular film was obtained using a conventional (Co)+(SiO₂) target, while by using a new type of sintered (Co)+(CoSi)+enriched(CoO) target, the oxygen composition in the granular film could be adjusted to be O/Si= 2 with grain isolated structure.