Study on low temperature and high deposition rate preparation method of Cobalt containing ferrite thin-film media using ECR sputtering

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In a conventional fabrication method of cobalt containing γ-Fe_2O_3 thin-film magnetic recording media, processing temperature higher than 250 degrees centigrade and two step fabrication process, that is sputter-deposition of CoO-Fe_3O_4 thin-films and transformation to Cobalt containing γ-Fe_2O_3 thin-films by annealing in air were necessary. In this study, novel sputtering using reactive and dense microwave plasma generated by electron-cyclotron-resonance (ECR phenomena) was introduced to achieve low-temperature and one step fabrication of these media. It was proved that the cobalt containing spinel ferrite thin-film media with a coercivity higher than 3000 Oe, well crystal orientation and very smooth surface (Ra is 0.2 to 0.4 nm) can be fabricated by using reactive ECR sputtering method at a low processing temperature (room temperature to 150 degrees centigrade) without any post oxidation processes.Recording and reproducing operation using inductive/MR merged flying head showed the cobalt containing ferrite thin-film media fabricated by the reactive ECR sputtering are utilizable without deposition of protective overlayer and surface polishing. Also, cobalt containing ferrite thin-films with high coercivity of about 2000 Oe were successfully deposited on organic flexible substrate such as PET and polyimide films by using ECR sputtering method. This experiment showed that application of the ferrite thin-films to the tape media was feasible. An ECR sputtering apparatus with high deposition rate was designed and developed.To summarize, the research goal of this study which was to develop low temperature and high rate fabrication method of ferrite thin-film media was satisfactorily achieved.