Core-shell magnetic nanoparticles for on-chip RF inductors

FeNi₃ based core-shell magnetic nanoparticles are demonstrated as the magnetic core material for on-chip, radio frequency (RF) inductors. FeNi₃ nanoparticles with 50-150 nm in diameter with 15-20 nm-thick SiO₂ coating are chemically synthesized and deposited on a planar inductor as the magnetic core to enhance both inductance (L) and quality factor (Q) of the inductor. Experimentally, the ferromagnetic resonant frequency of the on-chip inductors based on FeNi₃ core-shell nanoparticles has been shown to be over several GHz. A post-CMOS process has been developed to integrate the magnetic nanoparticles to a planar inductor and inductance enhancements up to 50% of the original magnitude with slightly enhanced Q-factor up to 1 GHz have been achieved.