Enhancement of Magnetic Properties and High-Frequency Inductance in the Bi-Layered FeN-FeNHf Thin Films

The planar spiral inductors consisting of patterned bi-layered FeN-FeNHf films with the high permeability were studied the performance with the change of bottom film. The permeability of the magnetic film was investigated by the shorted microstrip transmission line perturbation method and Landau–Lifshitz–Gilbert (LLG) theory in the bi-layered FeN-FeNHf films and single-layered FeNHf film. Experimental results indicated that permeability of the bi-layered FeN/FeNHf films with FeNHf bottom layer exhibited ~ 612, showing an increase of 51%, compared to that of single-layered FeNHf film above the frequency of 0.5 GHz. The resistivity of bi-layered FeN-FeNHf films was 485 μΩ·cm, which was about three times resistivity of single-layered FeNHf film of 139 μΩ·cm. Consequently, the enhanced inductance about 19% was found in the inductor based on the bi-layered FeN/FeNHf films. The enhancement of magnetization and permeability revealed that the ferromagnetic coupling between FeN and FeNHf films dominated the increased magnetization and the decreased in-plane magnetic anisotropy.