Study on low temperature and high deposition rate preparation method of Cobalt containing ferrite thin-film media using ECR sputtering

在传统的制备含钴γ-Fe_2O_3薄膜磁记录介质的方法中，需要高于250℃的加工温度和两步制备工艺，即溅射沉积CoO-Fe_3O_4薄膜和空气中退火转变为含钴γ-Fe_2O_3薄膜。在本研究中，利用电子回旋共振(ECR现象)产生的反应和致密的微波等离子体进行了新型的溅射，以实现低温一步法制备这些介质。结果表明，采用反应ECR溅射方法可以在较低的工艺温度下(室温至150℃)制备出矫顽力大于3000 Oe、晶向良好、表面非常光滑(Ra为0.2~0.4 nm)的含钴尖晶石铁氧体薄膜介质。利用感应/磁流变组合飞头进行记录和再现操作表明，反应ECR溅射制备的含钴铁氧体薄膜介质无需沉积保护层和表面抛光即可使用。同时，采用ECR溅射方法在PET和聚酰亚胺等有机柔性衬底上成功制备了高矫顽力约2000 Oe的含钴铁氧体薄膜。实验表明，铁氧体薄膜在磁带介质中的应用是可行的。设计并研制了一套高沉积速率的ECR溅射装置，较好地实现了本研究的研究目标，即开发低温高速制备铁氧体薄膜介质的方法。

In a conventional fabrication method of cobalt containing γ-Fe_2O_3 thin-film magnetic recording media, processing temperature higher than 250 degrees centigrade and two step fabrication process, that is sputter-deposition of CoO-Fe_3O_4 thin-films and transformation to Cobalt containing γ-Fe_2O_3 thin-films by annealing in air were necessary. In this study, novel sputtering using reactive and dense microwave plasma generated by electron-cyclotron-resonance (ECR phenomena) was introduced to achieve low-temperature and one step fabrication of these media. It was proved that the cobalt containing spinel ferrite thin-film media with a coercivity higher than 3000 Oe, well crystal orientation and very smooth surface (Ra is 0.2 to 0.4 nm) can be fabricated by using reactive ECR sputtering method at a low processing temperature (room temperature to 150 degrees centigrade) without any post oxidation processes.Recording and reproducing operation using inductive/MR merged flying head showed the cobalt containing ferrite thin-film media fabricated by the reactive ECR sputtering are utilizable without deposition of protective overlayer and surface polishing. Also, cobalt containing ferrite thin-films with high coercivity of about 2000 Oe were successfully deposited on organic flexible substrate such as PET and polyimide films by using ECR sputtering method. This experiment showed that application of the ferrite thin-films to the tape media was feasible. An ECR sputtering apparatus with high deposition rate was designed and developed.To summarize, the research goal of this study which was to develop low temperature and high rate fabrication method of ferrite thin-film media was satisfactorily achieved.