High-Q MEMS Inductors

Inductors have been used in RF circuits, such as voltage controlled oscillators, power amplifiers, mixers, etc. As the operating frequency of recent silicon RF IC's moves to the multi-GHz frequency range, it becomes difficult to achieve affordable Q-factors (>15) from on-chip inductors fabricated using conventional thin-film, planar IC processes.

Fully CMOS-compatible, highly-suspended spiral inductors have been designed and fabricated on standard silicon substrate (1~30Ωcm in resistivity) by our surface micromachining technology. We have achieved a peak Q-factor of 70 at 6GHz with inductance of 1.38nH (at 1GHz). This work has demonstrated that the our 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 IC's.

Figure 1. SEM photograph and performance of fabricated inductors

Related Publication
  1. J.-B. Yoon, et al, "3-D lithography and metal surface micromachining for RF and microwave MEMS", in IEEE MEMS '02 Tech. Dig., pp.673-676, Jan. 2002.