Electrical assessment of diamond MIM capacitors and modeling of MEMS capacitive switch discharging

Abstract

This paper presents the electrical assessment and modeling of the discharge process in RF MEMS capacitive switches with nanocrystalline diamond dielectric film. The assessment is performed by taking into account the detailed dc electrical characterization of the dielectric film at different temperatures with the aid of metal–insulator–metal (MIM) capacitors fabricated on the same die. The model assumes screening of trapped charges through carriers that are injected from the bottom electrode, transported through grain boundaries and redistributed across the diamond film surface through the sp2 state of non-diamond carbon. Simulated data and experimental results are found to be in excellent agreement, clearly indicating that nanocrystalline diamond can be considered as a MEMS dielectric with predictable discharging process.