Measurement of thin film permeability by direct contact and optimization

A highly sensitive method for obtaining the permeability of magnetic film without a limitation of sample size was developed based on the electrical impedance of magnetic film in contact with a copper conductor. The permeability of a CoNbZr thin film (25×25 mm2, 4 μm thick) was evaluated in the frequency range of 10 MHz-4 GHz, the measured values roughly corresponding to those obtained by the Landau-Lifshitz-Gilbert equation. The proposed method shows promise for permeability measurement of wafer-sized samples because the method is free of size limitation.