Magnetic Properties and GHz Permeability of (FeCo)-(SiO2) Films with High Saturation Magnetization of bcc-FeCo Phase

(Fe82Co18)-(SiO2) magnetic thin films with a bcc-FeCo crystal phase and SiO2 amorphous phase were deposited on glass substrates using synchronous triple-RF magnetron sputtering. Magnetic properties and high-frequency permeability characteristics of the films were investigated for an MMIC (Monolithic Micro wave a Integrated Circuit) inductor core. The film exhibited large anisotropy field Hk of 200 Oe and high electrical resistivity of 1000 μ Ω cm caused by addition of SiO2 into the film, and large saturation magnetization 4πMs of 14.5 kG caused by containing bcc-FeCo crystal with its saturation magnetization more than 23 kG. Reflecting these large Hk and 4πMs, a high resonance frequency of 4.4 GHz was obtained together with a higher relative permeability of about 100.The presented films containing bcc-FeCo crystal phase with high saturation magnetization have good potential for film inductor cores driving in the GHz frequency range.