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National Science Council of Republic of China

Chih-Ming Kuo

Po-Cheng Kuo

A method of producing high coercivity FePt&mdash;Si,N,granular composite thin films for magnetic recording media is invented. The method includes magnetron co-sputtering of FePt and Si,N,targets at controlled sputtering power and sputtering argon gas pressure to form a selective composition of granular FePt&mdash;Si,N,thin film on a low temperature substrate, then post-annealed in vacuum at selective time period and temperature. Two kinds of FePt targets can be used. One is the FePt alloy target. The other one is a composite target consisting of an iron disk overlaid with small Pt pieces. This arrangement provides a wide range of effective target compositions and therefore film compositions. FePt&mdash;Si,N,films were deposited on natural oxidized silicon wafer or quartz glass substrate at room temperature. The as-deposited film has soft magnetic properties and granular structure with soft magnetic &ggr;-FePt particles dispersed in amorphous Si,N,matrix. The as-deposited film cannot be used as magnetic recording medium due to its low coercivity. After annealing at controlled conditions for a desirable temperature and time period in vacuum, the film also has granular structure but the magnetic soft &ggr;-FePt phase is transformed into magnetic hard &ggr;,-FePt phase. This film has high coercivity and its magnetic easy-axis is parallel to the film plane. It may be used as high-density magnetic recording medium.

Manufacture method of high coercivity FePt-Si3N4 granular composite thin films

A method of producing SiNx protected amorphous Co-Tb thin films with high coercivity for longitudinal and perpendicular magnetic recording media is described. The method includes magnetron sputtering at controlled sputtering power and sputtering argon gas pressure to form a selective composition of amorphous Co-Tb thin film on a low temperature substrate. After the Co-Tb film is deposited, a protective SiNx layer with thickness of 100 .ANG. was produced on the film. The as-deposited film has an amorphous structure with a high value of coercivity, and its magnetic easy-axis is perpendicular to the film plane. This film can be used as a perpendicular magnetic recording medium. After low temperature annealing at controlled conditions for a desirable temperature and time period in vacuum, the film also has an amorphous structure but its magnetic properties are isotropic. This film can be used as a longitudinal magnetic recording medium.

Growing community of inventors

Taipei, Taiwan

Chih-Ming Kuo