CMOS-compatible surface-micromachined suspended-spiral inductors for multi-GHz silicon RF ICs

Fully CMOS-compatible, highly suspended spiral inductors have been designed and fabricated on standard silicon substrates (1/spl sim/30 /spl Omega//spl middot/cm in resistivity) by surface micromachining technology (no substrate etch involved). The RF characteristics of the fabricated inductors have been measured and their equivalent circuit parameters have been extracted using a conventional lumped-element model. We have achieved a high peak Q-factor of 70 at 6 GHz with inductance of 1.38 nH (at 1 GHz) and a self-resonant frequency of over 20 GHz. To the best of our knowledge, this is the highest Q-factor ever reported on standard silicon substrates. This work has demonstrated that the proposed microelectromechanical systems (MEMS) inductors can be a viable technology option to meet the today's strong demands on high-Q on-chip inductors for multi-GHz silicon RF ICs.