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

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/sub k/), thus improving high frequency characteristics. Planar-type spiral inductors using Ti/FeTaN films exhibit an inductance of /spl sim/1 /spl mu/H, resistance of /spl sim/2 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 a load current up to 300 mA.