Ultrahigh frequency properties of discontinuous CoFeB/SiO2 multilayer films with high resistivity

A series of multilayers of C036Fe46B18/SiO2 were fabricated by DC/RF magnetron sputtering, and further post-annealed in vacuum magnetic field at 200℃ for 2 h. The results show that the microstructures and electromagnetic properties of C036Fea6BIs/SiO2 multilayer films can be altered by varying the thickness of CoFeB and the process of annealing. High permeability along with high magnetic loss in the GHz frequency range is achieved in the optimized discontinuous multilayer films. Both real and imaginary parts of the complex permeability are larger than 260 at 1.6 GHz for this film, and the resistivity is as high as 1.4 mΩcm. The discontinuous Co36Fea6B18/SiO2 multilayers are supposed to serve as the microwave absorbers and EMI shielding materials in GHz range.