In an effort to get an excellent magnetic thin film for micro inductance cores, amorphous Co-based films with dispersed fine nitrides were investigated. Amorphous structure, almost zero magnetostriction (λ) and high electrical resistivity were confirmed in the sputter deposited films. TEM observation clarified that these films were composed of two kinds of amorphous phases. Soft magnetic properties of the obtained films were found to be related to the thickness of the film; as the thickness becomes less than 0.1 μm, the films become magnetically soft. Based on this relation, we attempted to make multilayered films consisting of the Co-based thin layers and BN ceramics thin layers and obtained excellent properties with high ρ (>300μΩcm), lowλ (1×10-6 ) and high μ ( > 1000) at high frequency near 100 MHz.
