Abstract
Soft magnetic (CoFeB)-(SiO2) films with highly electrical resistivity were deposited on glass substrates and hard-cured polyimide substrates by synchronous dual-rf magnetron sputtering. Frequency dependence of the permeability of the films was investigated. The films on both substrates exhibited highly resistive soft magnetic properties and a flat frequency profile with constant μr' over 800 MHz and a high resonance frequency of 1.5 to 1.8 GHz. The reciprocal of the loss factor tan δ (μr'/μr") at 400 MHz was about 30 for the film on a glass substrate.
Films deposited on hard-cured polyimide were applied to a 1-GHz drive frequency inductor. Inductance of the inductor increased by about 20% compared with that of the inductor without these films.
It was concluded that the (CoFeB)-(SiO2) films exhibited superior low loss characteristics in the range of 10 MHz to lGHz.
