Magnetic properties and frequency characteristics of (CoFeB)_x-(Si0_1.9)_i-x and CoFeB films for RF application

Abstract

(CoFeB)-(Si0_1.9) and CoFeB films were fabricated by synchronous triple RF magnetron sputtering with rotating a cylindrical electrode. Three types films for RF application in the range over 1 GHz were obtained, and these permeability characteristics and micro-structures were investigated.
The as-deposited films exhibited large anisotropy field H_κ in the range from 40 to 550 Oe, and exhibited highferromagnetic resonance (FMR) frequencies of 1.6-6.0 GHz in permeability characterisrtics. The films exhibited amorphous like or hetero-amorphous structures, which led to good soft magnetic properties with electrical resistivity ρ of 100-100, 000 μΩcm and saturation magnetization 4πM_s, of 6.5-20kG.
It was found that the obtained larger Hκ was effective to attain the higher frequency characteristics with the lower losses for RF inductor cores.