High-Q K-band integrated inductors using Cu/Ni nano-superlattice conductors

Ultra high quality factor (Q-factor) integrated inductors in K-band are reported where a maximum Q-factor of 55 has been achieved in the frequency band of 18-20 GHz. The proposed structure employs nanometer-thick alternating Cu and Ni multilayers, the so-called Cu/Ni nano-superlattice, for the conductor instead of a conventional thick single-layer Cu or Ag film. The conductor architecture efficiently overpasses the skin effect by cancelling the generated eddy currents inside the conductor allowing the current to flow through the whole volume of the conductor, resulting in the reduction of the resistive loss of the inductor. The inductors are nanomachined and measurement results show the highest Q-factor of an on-wafer K-band inductor reported to the best of the authors' knowledge.