Reliability characterization of MEMS switch using MIM test structures

Silicon nitride thin film dielectrics are used in capacitive radio frequency micro-electromechanical systems (MEMS) switches since they provide a low insertion loss, good isolation, and low return loss. The lifetime of these switches is believed to be adversely affected by charge trapping in the silicon nitride. The goal of this research was to characterize Si3N4-based MIM (Metal–Insulator–Metal) capacitors to describe the mechanisms responsible for the conduction and trapping behaviour in MEMS switches. The silicon nitride films were deposited by ICP chemical vapour deposition at room temperatures. The upper Si3N4 layer was removed by the reactive ion etching process (RIE) in order to provide contact paths to the bottom electrode. In the near-stoichiometric films, different electrical characterizations were performed to study dependence of the leakage current on different electrical parameters. It was concluded that the Poole–Frenkel mechanism dominated the conduction in the silicon nitride films at high fields.