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

Abstract

Soft ferromagnetic zero-magnetostrictive Co Nb Zr 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 μm, 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°C). Additionally, it is shown that the films do not suffer from rotatable magnetic anisotropy usually observed inconventional statically deposited films under magneticfield. Finally, a different origin of the magnetic anisotropyis suggested in dynamically deposited films.