Soft Magnetic Properties for Fe-B Films Sputtered in Ar+N₂ Plasma

Abstract

Fe-B films sputtered in Ar+N ₂ plasma were investigated in order to obtain film with high initial permeability. Importance was placed on elucidation of the relation between the initial permeability μ _i and parameters of the film structure such as the phase, grain size, and lattice strain. Fe-B (1 to 4 at% B) films sputtered in Ar+5%N ₂ plas-ma exhibit a high μ _i of about 2000 after annealing at 400 °C, and about 1000 after annealing at 500 °C. The results of X-ray and electron diffraction patterns indicate that films with high μ _i consist of the α phase. By comparing this with results for Fe-N films, it is suggested that the high μ _i of Fe-B-N films is caused by the reduction of grain sizes and induced lattice strain, as well as other metallurgical structures such as in homogeneities.