Effect of Post-Annealing on Ultra-High Frequency Properties of Amorphous Fe-Co-B Thin Films

In this paper, FeCoB amorphous thin films were deposited on glass substrates using a triode sputtering source under a uniform applied magnetic field. The as-deposited films exhibit a low coercivity of ~1.7 Oe, a high anisotropy field of ~37 Oe and 4[Pi] [M.sub.s] ~17.5 kG, when sputtered with a bias voltage of 180 V. The large anisotropy fields and saturations in these films result in a ferromagnetic resonance frequency as high as ~2.63 GHz, a relative permeability [micro]' of ~400-500 and a low dissipation [micro]' of 10-30 in the frequency range of 0.1-1 GHz. Upon subsequent annealing at 200-400 [degrees] C for 2 hrs, the magnetic properties of the films are found to be affected significantly. The magnetic properties of the as-deposited and the annealed films have been compared with a considering of the microstructure modification during annealing. Index Terms--UHF properties, soft magnetic properties, amorphous magnetic thin films, Fe-Co-B alloys.