High-quality radio-frequency inductors on silicon using a hybrid ferrite technology

We have realized millimeter-size rf inductors on silicon using a polyimide mold–copper electroplating coil technology. Subsequently, the coils are assembled with magnetic cover plates of commercially available bulk Ni–Zn ferrites of high resistivity. Using the magnetic flux-amplifying ferrite plates, we obtain a 40% enhancement of the inductance and a 25% enhancement of the quality factor (Q510– 20) for frequencies up to 0.2 GHz. Our results indicate the large potential of using bulk ferrites for RF applications in a hybrid inductor assembly process.