Development of high-rate sputtering system for Ba-ferrite thin film rigid disk for ultra high density magnetic recording

为了在不久的将来为高密度磁记录介质开发一种新的制备技术，建立了面向目标溅射系统。在该系统中，即使使用厚铁靶材，也能以较高的速率沉积铁磁薄膜。我们在前期的研究中发现，可以在较高的衬底温度下制备钡铁氧体薄膜。虽然钡铁氧体薄膜具有优异的磁记录介质特性，但不适合实际量产。在本研究中，我们提出了一种制作高密度高速率记录介质的新技术。在室温下沉积钡铁氧体薄膜，并依次退火结晶。对比常规直流磁控溅射系统和面向目标溅射系统制备的钡铁氧体薄膜的结晶温度，发现面向目标溅射系统制备的薄膜的结晶温度低于直流磁控溅射系统制备的薄膜。钡铁氧体薄膜的矫顽力在2 ~ 3kOe之间，垂直方向的方位比约为0.8。这些值适用于高密度磁记录介质。本研究采用MIG型磁头对钡铁氧体支承的硬碟进行了记录密度约为100kbpi的研究。通过优化制备条件，如沉积过程中的氧分压和退火时间，可以提高该值。从我们的研究结果来看，本项目提出的技术适用于实际的大量生产记录介质。

In order to develope a new fabrication technique for near future high density magnetic recording media, a facing target sputtering system has been built. In this system, the ferromagnetic thin films can be deposited with high rate even when the thick iron target was used. From our previous research, it was found that the Ba-ferrite thin films can be prepared at high substrate temperature. Although the Ba-ferrite thin films with excellent characteristics for magnetic recording media, it is not suitable for practical mass prodauction. In this study, we proposed a new technique for fabrication of high density recording media with high rate.The Ba-ferrite thin films were deposited at room temperature and succsessively annealed to crystallize. In comparison with the crystallization temperature of Ba-ferrite thin films prepared both a conventional dc magnetron sputtering system and the facing targets sputtering system, it was found that the crystallization temperature of the films prepared by the facing target sputtering system is lower than of the films prepared by the dc magnetron sputtering system.The coercivities of the Ba-ferrite thin films are in the range from 2 to 3kOe and squareness ratio is about 0.8 in perpendicular direction. These vakues are suitable for high density magnetic recording media.The recording density obtained in this research is about 100kbpi for the Ba-ferrite supttered rigid disks by using a MIG type head. This value will be improved by optimizing the preparation conditons such as oxygen partial gas pressure during the deposition and annealing time.From the results of our reseach, it was found that the technique propsed in this project is applicable for practical mass production of recording media.