Thickness Effect on 1 GHz Permeability of (CoFeB)--(Si[O.sub.2]) Films with High Electrical Resistivity

Highly resistive (CoFeB)-(Si[O.sub.2]) films for magnetic core of 1 GHz driving inductor were deposited on glass substrates by synchronous dual-rf magnetron sputtering. Permeability characteristics in the range of a few GHz were investigated. The thickness effect on the reciprocal of the loss factors of tan [Delta] ([[micro]'.sub.r]/[[micro]'.sub.r]) were investigated at 1 GHz. The film exhibited the maximum value of ([[micro]'.sub.r]/[[micro]'.sub.r]) of 5.7 for film thickness d = 0.1 [micro]m, with relative permeability of 120-150 and resonance frequency [f.sub.r] = 1.6-1.9 GHz. The result shows good potential for magnetic core of 1 GHz driving inductor. Index Terms--(CoFeB)-(Si[O.sub.2]) films, GHz range, high resistivity, low loss factor, magnetic core, permeability.