Highly resistive soft magnetic (CoFeB)-(SiO2) films were deposited on glass substrates and polyimide substrates.The frequency dependence of the permeability of the films was investigated in the range of a few GHz. The films exhibited flat frequency profiles with constant μr' up to 800 MHz, and high resonance frequencies of 1.1-1.8 GHz. The thickness dependence of the reciprocal of the loss factor tan δ(μr'/μr") was compared at 1 GHz for the films deposited on glass substrates. Films with a thickness of 0.1 μm exhibited a low loss factor over 5, which indicated good potential for application in a 1 GHz-inductor.
