Very high electrical resistivity and heteroamorphous structure of soft magnetic (Co/sub 35.6/Fe/sub 50/B/sub 14.4/)-(SiO/sub 2/) thin films

Abstract

(Co/sub 35.6/Fe/sub 50/B/sub 14.4/)-(SiO/sub 2/) soft magnetic films with electrical resistivity of over 10000 /spl mu//spl Omega/ /spl middot/ cm (1 /spl times/ 10/sup -4/ /spl Omega/m) were fabricated on glass substrates by using synchronous triple-RF magnetron sputtering. The magnetic properties, high-frequency permeability characteristics, and microstructure of the films were investigated. Maximum electrical resistivity of about 115600 /spl mu//spl Omega/ /spl middot/ cm (1.156 /spl times/ 10/sup -3/ /spl Omega/m) was obtained with a large uniaxial anisotropy field H/sub k/ of about 250 Oe, a hard axis coercivity H/sub ch/ of 5.6 Oe, and a saturated magnetization 4/spl pi/M/sub s/ of 8.3 kG. The real part of the relative permeability /spl mu/'/sub r/ was about 50, which exhibited a good flat frequency dependence up to 2 GHz. The resonance frequency was higher than 3 GHz. It was found that the heteroamorphous films had soft magnetic properties with high resistivity of over 10000 /spl mu//spl Omega/ /spl middot/ cm and high resonance frequency. The films are good candidates for core application in the gigahertz range.