High frequency characteristics of as-sputtered Co-Ni-Fe-N soft magnetic thin films

Co-Ni-Fe-N soft magnetic thin films with excellent high frequency characteristics were fabricated by a N₂ reactive RF magnetron sputtering method. The nitrogen partial pressure (P_N2) was varied in the range of 0~10%. As P_N2 increases in this range, the saturation magnetization (B_s) linearly decreases from 19.8 kG to 14 kG and the electrical resistivity (ρ) increased from 27 μΩcm to 155 μΩcm. The coercivity (H_c) exhibits the minimum value at 4% P_N2. The magnetic anisotropy field (H_k) is in the range of 20~40 Oe. The high frequency characteristics of (Co_22.2Ni_27.6Fe_50.2) _100-xN_x films are excellent in the range of 3~5% P _N2. Especially, the effective permeability of the film fabricated at 4% P_N2 is about 800, which is maintained up to 600 MHz. This film exhibits B_s of 17.5 kG, H_c of 1.4 Oe, ρ of 98 μΩcm, and H_k of about 25 Oe. The corrosion resistance of (Co_22.2Ni_27.6Fe_50.2 )_100-xN_x is improved with the increase of N concentration