High-Frequency Resistivity Measurement Method for Multilayer Soft Magnetic Films

We present a noncontact method to measure the resistivity of multilayer magnetic thin films under high-frequency excitation. A multilayer thin-film magnetic material separated by dielectric has been used in microfabricated magnetic components in power applications. High-frequency resistivity is necessary for predicting core loss in magnetic materials. Traditional measurement methods using contacting probes cannot provide a reliable measurement of the resistivity of multilayer thin-film materials. Noncontact methods eliminate the use of electrical probes. Eddy-current loss induced by an applied external magnetic field is measured and the high-frequency resistivity of multilayer material is extracted from eddy-current loss measurements. The application of this method to measure the resistivity of multilayer thin-film materials and magnetic materials is investigated. The high-frequency resistivity of a 6-μm-thick multilayer Co-Zr-O thin-film magnetic granular material is measured. Comparisons between theoretical and experimental results are presented.