Abstract Monolithic integration of high-frequency magnetic components such as hexaferrite circulators at the wafer scale can lead to a significant improvement in radio frequency (RF) circuit performance and functionality. However, current methods to monolithically integrate hexaferrite films, such as liquid phase epitaxy, require high temperature (> 900 °C) annealing to create crystalline alignment, which is not compatible with integrated circuit process temperatures ( 50 μm). In this work, we report the synthesis of pure phase, faceted, and high crystallinity hexaferrite [SrFe12O19] nano-platelets using a direct hydrothermal approach, followed by self-assembly of binder free SrFe12O19 films with high film density and high magnetic isotropy. The nano-platelets exhibit high staturation magnetization (~ 60 emu/g) and coercivity (Hc) of 815 Oe. The magnetic films exhibit dense nano-particle concentration and a magnetic squareness (Mr/Ms) of 0.7. They can be patterned using a selective assembly process through a thick photoresist mask. Thicknesses of up to 70 μm have been deposited on 4-in.-diamater wafers.

中文翻译：

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用于磁性元件晶圆级图案化的 SrFe12O19 纳米片的合成和无粘合剂组装

摘要 高频磁性元件（如晶片级六铁氧体环行器）的单片集成可显着提高射频 (RF) 电路的性能和功能。然而，目前单片集成六铁氧体薄膜的方法，例如液相外延，需要高温 (> 900 °C) 退火来产生晶体排列，这与集成电路工艺温度 (50 μm) 不兼容。在这项工作中，我们报告了使用直接水热法合成纯相、多面和高结晶度六铁氧体 [SrFe12O19] 纳米片，然后自组装具有高膜密度和高磁各向同性的无粘合剂 SrFe12O19 膜。纳米片表现出高饱和磁化强度 (~ 60 emu/g) 和 815 Oe 的矫顽力 (Hc)。磁性膜表现出致密的纳米粒子浓度和0.7的磁性矩形度(Mr/Ms)。它们可以通过厚光刻胶掩模使用选择性组装工艺进行图案化。在直径为 4 英寸的晶片上沉积了高达 70 微米的厚度。