Stacked-spiral RF inductors with fully-filled vertical nanoparticle magnetic core

A new concept of stacked-spiral inductor fully-filled with VERTICAL closed-circuit nano-particle magnetic core in CMOS is reported. Prototypes, fabricated in a six Al metal layer CMOS backend process using ferrite nanoparticles, show a high inductance-density up to 920 nH/mm
²
in multi-GHz, which is promising for making super compact inductors in RF system-on-a-chip (SoC).