Bidirectional ferromagnetic spiral inductors using single deposition

Size reduction for spiral inductors is investigated. We reveal bidirectional ferromagnetic inductors with an ∼30% to 135% increase in L over the air-core value. This is advantageously realized by using single deposition. The realization uses above-IC techniques and high-magnetization FeHfN laminated films. We also report a quality factor of ∼10 at 1.5 GHz, which is mitigated while realizing high FMR frequency (up to 6 GHz). This leads to considerations on nonmagnetic excess losses. Finally, a surface reduction of 25% to 50% for conventional spirals is demonstrated.