Study on Development of High Rate Sputtering Apparatus for Producing Perpendicular Magnetic Recording Tape.

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One of the most promising candidate system to achieve ultra high density magnetic recording is perpendicular magnetic recording system using Co-Cr thin film tape media. It is required to develop the continuous thin film coating system on polymer tape substrate in order to prepare such recording tape using Co Cr thin film. Facing Targets Sputtering (FTS) system has many merits in depositing thin film, such as high rate film deposition at low working gas pressure without plasma bombardment. The FTS system with role coating system has been developed in this study. This machine worked in the condition of Ar gas pressure as low as 0.1mTorr where conventional sputtering system can not work. Co-Cr thin film with good c-axis orientation can be prepared without any warp nor transformation of tape substrate caused by heat at high deposition rate of 1000A/min.. Internal stress of deposited films changed with working gas pressure, and indicates zero for films prepared at about 0.5mTorr. This stress-free thin film is very good for flexible recording media from the stand point of tribological investigation. Multilayered films constructed with 200A-thick Co-Cr layers and 50A-thick Carbon layers have been prepared so as to construct films with only fine particulates. It is demonstrated that multilayered structure constructed only Co-Cr layers becomes one of the method for controlling perpendicular coercivity. It is also investigated that two step deposition method in role coating system is very useful to avoid the degradation of crystallinity and large c-axis canting angle which occurs at the edge part of deposition area. It is investigated that Only 100A-thick initial layer constructed with depositing particles with vertical incidence to the substrate. This result means FTS system can achieve ultra high rate deposition without reduction of deposition rate.