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 × 2.5 mm, 2 turns) was placed in proximity of a (Co 25 Fe 75 ) 90 B 10 film (45 mm × 25 mm, 0.53 μm 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.