Microwave Electromagnetic Properties of Discontinuous CoFeB-SiO_2 Magnetic Multilayer Films

A series of multilayers of CoFeB-SiO_2 was fabricated by using DC/RF magnetron sput- tering,and then annealed in vacuum at different temperatures.The results show that microstructures and electromagnetic properties of the CoFeB-SiO_2 multilayer films can be altered by varying the volume fraction of SiO_2 and the annealing temperature.High permeability along with high magnetic loss in the GHz frequency range is achieved in the optimized discontinuous multilayer films.Both real and imagi- nary part of the complex permeability are larger than 260 at 1.5GHz for these films,and the resistivity is as high as 1.38mΩ·cm.The CoFeB-SiO_2 multilayers are supposed to serve as the microwave absorbers in GHz range.