Optimization of 0-level packaging for RF-MEMS devices

This paper reports on the optimization of the 0-level package for RF-MEMS devices like switches and tunable capacitors. The 0-level package consists of an on-chip cavity obtained by flip-chip mounting a capping chip over the RF-MEMS device, using BCB as the bonding and sealing material. A process for realizing low-profile packages, with caps less than 100 /spl mu/m thick, is described. Coplanar RF feedthroughs are implemented using BCB as the dielectric. It is experimentally shown that a 0-level package using capping chips made of low-loss high-resistivity materials and having a cavity height larger than about 45 /spl mu/m, has a negligible impact on the microwave characteristics of an RF-MEMS device, built on a 50 /spl Omega/ CPW line with ground-to-ground spacing of 150 /spl mu/m.