Low-voltage large-value tunable capacitors using selfaligned HARPSS

This paper presents a silicon microfabrication technique for the implementation of large-value one-port and two-port tunable capacitors with very small tuning voltages. The proposed process offers very high aspect- ratio narrow vertical gaps of different sizes in a self- aligned manner, allowing the realization of in-plane tunable capacitors in a small area. A continuous tuning of 240% is achieved for a 15 pF two-port capacitor with the application of 3.5 V. A 106 pF one-port capacitor occupies an area of 8 mm² and is tuned to 130 pF with a tuning voltage of 0.9 V.