Improvement of crystallographic characteristics of CoCrTa thin film using double underlayer
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Improvement of crystallographic characteristics of CoCrTa thin film using double underlayer Y.J.Kim*, S.H.Kong**, S.Nakagawa**, M.Naoe** and K.H.Kim* *School of Electrical & Electronic Eng., Kyungwon Univ., Kyunggi-do 461-701, Korea **Dept. of Physical Electronics, Tokyo Institute of Technology, Tokyo 152-8522, Japan ABSTRACT High c-axis oriented CoCr-based thin films are expected for ultra-high density recording media in perpendicular magnetic recording system. In order to improve dispersion angle of caxis of CoCr-based for perpendicular magnetic recording media, we prepared trilayered film with double underlayer using New Facing Targets Sputtering apparatus. The thickness of magnetic layer CoCrTa and double underlayer, such as interlayer Pt, paramagnetic CoCr, underlayer Ti was fixed 50nm and 20nm respectively. In order to prepare the thin film, we fixed argon gas pressure 1mTorr, substrate temperature 250°C and input current 0.5A. The crystallographic characteristics of CoCrTa layer with varying interlayer thickness (0- 20nm) have been investigated. By the result, the CoCrTa trilayered thin film with interlayer Pt showed good c-axis orientation 3.45° and 3.62° at thickness 5nm and 10nm respectively. However, CoCrTa thin film using interlayer paramagnetic CoCr showed 8.28° and 8.62° at thickness 5nm and 10nm respectively.
INTRODUCTION Perpendicular magnetic recording [1] is regarded as a candidate for achieving ultra-high density above 100Gbits/in2 [2]. Among the rest thin films of Co-Cr alloy with thickness of several tens of nanometers are known as most compatible media due to easiness of thin film preparation, and control of coercivity and saturation magnetization. In these thin film media of Co-Cr alloy the most important things are realization of being low-noise and high recording density. To overcome these, it is necessary to be thinner the thickness of ferromagnetic recording layer, and necessary to be finer grains. However, because of the formatted initial layer that exhibited to bad perpendicular characteristics, it should be improve magnetic characteristic of magnetic layer and be thinner the initial layer as much as a possible [3]. In this study, the effects of inserting interlayer to CoCrTa/Ti doublelayer media for perpendicular magnetic recording are observed.
EXPERIMENTAL DETAILS Films were prepared by using the New Facing Targets Sputtering apparatus with box type T3.7.1
sputtering units. FTS [4,5] was in which substrate was located apart from plasma, so called plasma free, and could restrain bombardment to substrate from γ-electron and negative ion as high-energy particles and maintain the stable electrical discharge at low gas pressure. Forming the magnetron mode with varying location of a permanent magnet, NFTS [6] can confine plasma effectively and expand efficiency area of target. Also, FTS can prepare the thin film that has a good compositional segregation and spinodal decomposition. Ti [7] as underlayer, CoCrTa as magnetic layer, and an interlayer of Pt and paramagnetic CoCr were deposite
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