Characteristics of Double Planar Micro-Inductor with Patterned NiFe Thin-Films for DC/DC Integration

This paper proposes a double-planar-coil microinductor with patterned permalloy magnetic film for high frequency DC–DC integration. The effects of magnetic film’s patterning and thickness on the inductance and quality factor of the micro-inductor are investigated by using COMSOL Multiphysics software. Simulation results indicate that the magnetic film improves the inductance of microinductor effectively and patterning of the magnetic film reduces eddy current loss in high frequency range. The micro-inductor is fabricated by using micro-electro-mechanical systems (MEMS) technique. The inductance of approximately 2.17 μH at 1.5 MHz and the quality factor of 2.8 are achieved for the microinductor with patterned magnetic film. The performances of the micro-inductor applied in a low-power DC/DC converter are tested. The results indicate that the micro-inductor with the patterned magnetic film effectively has improved inductance and quality factor compared to that with non-patterned magnetic film. The maximum efficiency of measured converter is 67% at 1.5 MHz and the output current is 100 mA.