Ultra-high electrical resistivity and hetero-amorphous structure of GHz soft magnetic (CoFeB)-(SiO/sub 2/) thin film

Summary form only given. We have previously reported that our hetero-amorphous structured films are an excellent candidate for the magnetic core materials for GHz frequency use because of their high resistivity (Munakata et al. (2001)). However, a further increase of the resistivity is desired for sufficient removal of eddy current loss. In the present work, (Co/sub 35/Fe/sub 50/B/sub 14.4/)-(SiO/sub 2/) soft magnetic films with ultra-high resistivity of 116,000 /spl mu//spl Omega/cm were fabricated, which is 30 times larger than the maximum published value at present. The microstructure of the film associated with the very high resistivity was investigated. The films with thickness of 0.5 /spl mu/m were deposited on glass substrates by synchronous triple-rf magnetron sputtering. The permeability in a few GHz range was measured by a permeance meter. The structure of the film was analyzed by transmission electron microscopy (TEM).