Soft-magnetic properties of Fe-Co-B thin films for ultra-high-frequency applications

Fe(67)Co(18)B(15) amorphous thin films were sputter deposited on glass substrates under a uniform applied magnetic field. The films exhibit excellent soft-magnetic properties of 4 pi M(s)similar to 17.5 kG, H(c)similar to 0.3 Oe, and H(k) (anisotropy field) similar to 22 Oe. The ultra-high-frequency performance on these films was studied and the relative permeability mu' is shown to be as high as similar to 740 and almost constant to at least 1 GHz. The combination of high 4 pi M(s) and relatively high H(k) in these films is believed to be partly responsible for the excellent ultra-high-frequency behavior. The soft-magnetic properties of these films show a strong dependence on the film deposition bias voltage, which presumably changes the microstructure of the films and the related magnetic anisotropy. (C) 2000 American Institute of Physics. {[}S0021-8979(00)22508-5].