Thin Film Permeability Evaluation Based on Skin Effect Using Meander-Type Probe Up to 10.6 GHz

A highly sensitive and broadband method of obtaining thin film permeability without limitations in sample size was developed based on the high-frequency impedance change because of skin effect. A meander-type probe (3.5 mm
$\,\times\,$
2.5 mm, 2 turns) was placed in proximity of a (Co
$_{25}$
Fe
$_{75}$
)
$_{90}$
B
$_{10}$
film (45 mm
$\,\times\,$
25 mm, 0.53
$\mu$
m thick), and the permeability was optimized by Newton–Raphson method. The measured values are in good agreements with theoretical values based on the Landau–Lifshitz–Gilbert equation up to 10.6 GHz. The proposed method shows promise for measuring the permeability of wafer-sized samples in line because it is not restricted by size limitations.