Skin effect suppression in multilayer thin-film spiral inductor taking advantage of negative permeability of magnetic film beyond FMR frequency

This paper describes the study on skin effect suppression in multilayer thin film coplanar transmission lines and spiral inductors taking advantage of negative permeability of ferromagnetic film beyond the ferromagnetic resonance (FMR) frequency. The Al/NiFe and Cu/CoZrNb multilayered thin film coplanar transmission lines are studied. The measured resistance of both coplanar transmission lines becomes small when the real part permeability is negative, as the number of layers is more than 15, suggesting that each metal layer should be thinner than the skin depth of original metal layer. As for the spiral inductor consisting of Cu/CoZrNb multilayered thin film, the quality factor exhibited 14.6 at 5.2 GHz at largest.