Fabrication of high frequency DC-DC converter using Ti/FeTaN film inductor

Abstract

We fabricated a planar-type film inductor with good high frequency characteristics using a FeTaN soft magnetic film. While FeTaN films inherently show good soft magnetic properties and high saturation magnetization, addition of Ti underlayer with a combination of magnetic field annealing leads to an increase of anisotropy field (H-k), thus improving high frequency characteristics. Planar-type spiral inductors using Ti/FeTaN films exhibit an inductance of similar to1 muH, resistance of similar to2 ohm, and Q factor of 2.3 at 2 MHz. We also fabricated a hybrid ZVS-CV buck converter using the film inductor. The converter shows about 80% of the conversion efficiency at 1.2 MHz, which withstands the load current up to 300 mA.