A novel low cost failure analysis technique for dielectric charging phenomenon in electrostatically actuated MEMS devices

This work presents a novel failure analysis technique for the dielectric charging phenomenon in electrostatically driven MEMS devices. The new reliability assessment methodology makes use of Kelvin Probe Force Microscopy (KPFM) and it targets in this specific work thin PECVD silicon nitride films for electrostatic capacitive RF MEMS switches. The proposed technique took advantage of the AFM tip to simulate charge injection through asperities then measure the induced surface potential. The impacts of bias amplitude, bias polarity, and bias duration employed during charge injection have been explored. Various parameters have also been investigated: dielectric film thickness, substrate nature, and SiN material deposition conditions. FTIR and XPS material characterization techniques have been used to determine the chemical bonds and compositions, respectively, of the SiN films being investigated. The required samples for this technique consist only of thin dielectric films deposited over planar substrates and no photolithography steps are required. Therefore, the proposed methodology provides a low cost and quite fast solution compared to the currently available methods.