High frequency magnetic properties of CoZrNb thin films deposited by dynamic sputtering technique for GHz Si-integrated planar inductors

摘要

Soft ferromagnetic zero-magnetostrictive CoNbZr thin films have been dynamically deposited by dc planar magnetron sputtering onto continuously transported substrates. No magnetic field has been applied to the films during deposition. The films reveal a well-defined in plane uniaxial anisotropy with an easy axis aligned along the direction of substrate motion. As a result, an anisotropy field of 75 Oe and a ferromagnetic resonance frequency of 2.6 GHz have been measured. The study of the relationship between magnetic properties and film thickness points out a critical thickness around 0.3 mu m, above which the films exhibit a stripe-domain-like behavior which is detrimental for the high frequency use. The thermal stability of the films is found to be usual as regular amorphous core materials (stable up to 300 deg C). Additionally, it is shown that the films do not suffer from rotatable magnetic anisotropy usually observed in conventional statically deposited films under magnetic field. Finally, a different origin of the magnetic anisotropy is suggested in dynamically deposited films.