Micro-Scaled on-chip 30-turn Toroidal Inductor
This SEM image shows the micro-scaled on-chip 30-turn toroidal inductor fabricated on SiO2-coated Si substrate by standard photolithography technique. The diameter denoted in D of the inductor is 240 μm. A 160 nm thick ring-shaped core of SiO2 is used to isolate top metal (Au, 220 nm) and bottom metal (Au/Cr, 35 nm/5 nm). Ground-signal-ground pads are designed for high frequency measurement. The best inductor shows the maximum quality factor of 183 at an operating frequency of 28.8 GHz, in which the D and the dielectric layer thickness are 960 μm and 5 μm, respectively. Details please consult with Professor Wu, and refer to the paper submitted IEEE Transitions on Magnetics.