Study on Preparation Method of Ultra-High-Density Magnetic Recording Media by Sputtering Using Electron Cyclotron Resonance Microwave Plasma

为了实现超高密度磁记录，要求记录介质具有由纳米尺度的铁磁区和非磁区组成的磁性微结构。本研究的目的是建立用于超高密度磁记录的Co-Cr介质的制备方法。介绍了一种新的电子回旋共振微波等离子体(ECR)溅射方法，该方法比传统的二极管溅射方法更适合于精确控制等离子体。在薄膜沉积过程中，等离子体中的Ar离子被等离子体和衬底电压之间的电压差加速，并对磁性微结构的产生产生强烈的影响。在较高的Ar气压为8×10~(-2)Pa和较长的靶-衬底距离230 mm的条件下，获得了较低的离子加速电压20V。在上述溅射条件下制备的Co-Cr介质具有良好的晶体取向、大于1400Oe的垂直矫直力和大于4kO的垂直磁各向异性场。为了在大范围内控制离子加速电压，在衬底支架附近安装了辅助线圈，改变了沉积室中的磁场分布。在离子加速电压为11V时，离子加速电压降至11V。在离子加速电压为11V时沉积的Co-Cr薄膜实现了纳米级颗粒成分的分离。通过记录特性的测量，证明了Co-Cr介质具有超高密度记录分辨率和低噪声特性。

To achieve ultra-high density magnetic recording, It is required that recording media have magnetic microstructure which consists of nano-meter size ferro-magnetic regions and non-magnetic regions. The purpose of this research is to establish the Co-Cr media preparation method for ultra-high density magnetic recording. In this research, a new sputtering method using electron cyclotron resonance microwave plasma (ECR sputtering) was introduced which is more suitable to control a plasma precisely than the conventional diode sputtering method.Ar ions in plasma accelerated by the voltage difference between a plasma and a substrate voltage bombared the substrate during film deposition, and make drastic influence on a creation of magnetic microstructure. Ion accelerating voltage of 20V which is a relatively low value is obtained at high Ar pocess gas pressure of 8*10^<-2>Pa and long target-to-substrate distance of 230mm. The Co-Cr media fabricated in the above mentioned sputtering condition showed good crystal orientation, high perpendicular coercivity over 1400Oe and large perpendicular magnetic anisotropy field exceeding 4kOe.To control the ion accelerating voltage in wide range, the magnetic field distribution in a deposition chamber was changed using an auxiliary coil installed near the substrate holder. At cusp magnetic field, ion accelerating voltage was decreased to 11V.The compositional separation with nano-meter size in grains which was achieved in the Co-Cr films deposited at ion accerralating voltage of 11V.From the measurement of recording characteristics, it was proved that the Co-Cr media showed ultra-high density recording resolution and low noise characteristics.