以磁控濺鍍法鍍製鐵鈷鋯氧/二氧化鋯多層軟磁薄膜及其靜磁性質與高頻特性之探討(Static and High Frequency Magnetic Properties of (FeCoZrO/ZrO2)n Soft Magnetic Thin Films Fabricated by Magnetron Sputtering)

Abstract

Soft magnetic thin films with high saturation magnetization and suitable uniaxial anisotropy are of great interest in micro-inductors for the magnetic device application. The purpose of this thesis is focused on the soft magnetic multilayered film (FeCoZrO/ZrO2)n. The films were fabricated by reactive magnetron sputtering. The thickness of FeCoZrO films, the stacking levels of multilayered films and the sputtering modes of ZrO2 were altered to study how the microstructure, interface roughness and stress behavior in the as-fabricated films affected the static magnetic behavior, electrical properties, high frequency characteristics and magnetic domains. The resistivity of the (FeCoZrO/ZrO2)n films increased with increasing stacking levels. In addition, the effects of the residual stress and interface roughness on magnetic behavior and magnetic domains would arise when the multilayered films were deposited. Two experiments were designed to explore which factors would affect the magnetic behavior of the films. Firstly, a series of single-layered FeCoZrO (t nm)/ZrO2 (5 nm) films with various thickness t were fabricated. Secondly, the sub-layer thickness t in multilayered (FeCoZrO(t nm)/ZrO2(5 nm))n film was changed when the total film thickness was fixed. When the thickness t increased, Hc became smaller, regardless of multi-layers or single-layers. Hence, the variation of Hc was partly attributed to interface roughness. Moreover, the magnetostriction constant of FeCoZrO was measured to be 8.0E-5. Hence, the interface roughness and residual stress were critical to the magnetic behavior, Hc especially. The effect of the interface on the magnetic behavior was further studied. A series of FeCoZrO (70 nm)/ ZrO2 films, where the ZrO2 was prepared by different sputtering modes, were synthesized. The roughness of ZrO2 interface was altered by different sputtering modes, such as the change of substrate bias and types of power generator. The static magnetic properties, such as coercivity, squareness and uniaxial anisotropy field along hard axis, are affected by the interface roughness significantly. The magnetization reversal of FeCoZrO (70 nm)/ZrO2 is changed from coherent rotation to domain wall motion with increasing interface roughness. Moreover, ferromagnetic resonance frequency is enhanced and the real part of the complex permeability is reduced with decreasing interface roughness. These phenomena could be explained by the demagnetization energy induced by interface roughness.