Magnetic tunneling junction (MTJ) materials such as CoFeB, Co, Pt, MgO, and the hard mask material such as W and TiN were etched with a reactive ion beam etching (RIBE) system using H2/NH3. By using gas mixtures of H2 and NH3, especially with the H2/NH3( 2:1) ratio, higher etch rates of MTJ related materials and higher etch selectivities over mask materials (>30) could be observed compared to those etching using pure H2( no etching) and NH3. In addition, no significant chemical and physical damages were observed on etched magnetic materials surfaces and, for CoPt and MTJ nanoscale patterns etched by the H2/NH3( 2:1) ion beam, highly anisotropic etch profiles >83° with no sidewall redeposition could be observed. The higher etch rates of magnetic materials such as CoFeB by the H2/NH3( 2:1) ion beam compared to those by H2 ion beam or NH3 ion beam are believed to be related to the formation of volatile metal hydrides (MH, M = Co, Fe, etc) through the reduction of M-NHx( x = 1 ∼ 3) formed in the CoFeB surface by the exposure to NH3 ion beam. It is believed that the H2/NH3 RIBE is a suitable technique in the etching of MTJ materials for the next generation nanoscale spin transfer torque magnetic random access memory (STT-MRAM) devices.

中文翻译：

---

使用 H2/NH3 反应离子束蚀刻磁性隧道结材料的特性

磁性隧道结 (MTJ) 材料（例如 CoFeB、Co、Pt、MgO）和硬掩模材料（例如 W 和 TiN）通过使用 H2/NH3 的反应离子束蚀刻 (RIBE) 系统进行蚀刻。通过使用 H2 和 NH3 的气体混合物，尤其是 H2/NH3(2:1) 的比例，与使用纯 H2 的蚀刻相比，可以观察到 MTJ 相关材料的更高蚀刻速率和对掩模材料的更高蚀刻选择性 (>30) （无蚀刻）和 NH3。此外，在蚀刻的磁性材料表面上没有观察到明显的化学和物理损伤，对于由 H2/NH3(2:1) 离子束蚀刻的 CoPt 和 MTJ 纳米级图案，高度各向异性的蚀刻轮廓 >83° 且没有侧壁再沉积可以被观察。H2/NH3(2: 1) 与 H2 离子束或 NH3 离子束相比，离子束被认为与通过还原 M-NHx( x = 1 ∼ 3）通过暴露于NH3离子束在CoFeB表面形成。人们认为，H2/NH3 RIBE 是用于下一代纳米级自旋转移矩磁性随机存取存储器 (STT-MRAM) 器件的 MTJ 材料蚀刻的合适技术。