The key technologies in silicon based microwave and RF MEMS device fabrication

In this paper, the key fabrication technologies used for microwave and radio frequency MEMS devices, namely RF-MEMS, are discussed. Our studies focus on the fabrication of inductor, capacitor and switch on silicon substrate. To reduce the substrate effect, substrate modification via porous silicon method is introduced, and high Q inductor has been realized porous silicon modification substrate is showed. The polyimide (PI) sacrificial layer technology is used for the switch and capacitor fabrication. To reduce the ohmic loss in transmission line for the RF devices used in the high frequency (around 2 GHz), a special process sequences is developed to realize the thick metallic plating. To illustrate the integrative capacity of RF MEMS with CMOS circuits, a VCO with flip-chip MOS and MEMS packaging is designed, which present minimized parasitic effects in the device interconnection.