Soft magnetic and microwave characteristics of amorphous FeCoBNi–Al2O3 films deposited by RF magnetron co-sputtering

A series of FeCoBNi–Al2O3 films were fabricated on glass and polymer substrates by means of RF magnetron co-sputtering. Firstly, the FeCoB films with Al2O3 addition were investigated. To further improve the microwave characteristics of the films, the effects of the Ni content on the soft magnetic properties and microwave characteristics of (Fe40Co40B20)97−xNix–(Al2O3)3 films were studied. As a consequence (Fe40Co40B20)97–(Al2O3)3 films doped with 28.64 at.% of Ni exhibit excellent properties with high saturation magnetization (4πMs) of 1.67 T, high resonant frequency (fr) of 2.58 GHz, high electrical resistivity (ρ) of 235.85 μΩ cm and the real part of permeability is about 300, which is maintained up to 2 GHz. These results show that the presented films possesses potential in designing micro-magnetic devices design for Monolithic Microwave Integrated Circuit (MMIC).

► A series of FeCoB films with the Al2O3 and Ni doping have been fabricated using RF magnetron co-sputtering.
► The effects of the Ni content on the electromagnetic parameters of (FeCoB)97-xNix–(Al2O3)3 have been explained based on our systematic experimental results.
► Microwave characteristics of (FeCoB)–(Al2O3) films can be significantly improved by doping the film with 28.64 at.% Ni.