Measurement and analysis of substrate leakage current of RF mems capacitive switches

This paper focused on a new direction of study on leakage current called substrate charge injection. The substrate leakage current of capacitive RF micro-electro-mechanical-system (MEMS) switches was measured, and the conduction mechanism was estimated. The study of the leakage current conduction mechanisms of the substrate dielectric film shows that leakage is mainly induced by hopping conduction at low electric fields, whereas both Schottky emission and hopping conduction may contribute to the leakage current at high fields. The quantitative relationship between the substrate leakage current and the dielectric layer leakage current was also determined for the first time. In the case of low drive voltage (0–30 V), the substrate leakage current significantly contributes to the total leakage current. Results show that the charging properties of the substrate should not be neglected at low drive voltage because such properties could significantly affect the functionality and reliability of RF MEMS switches.