Assessment of dielectric charging in electrostatically driven MEMS devices: A comparison of available characterization techniques

摘要

The present work investigates the results of different characterization methods for the dielectric charging phenomenon applicable to metal-insulator-metal (MIM) capacitors and electrostatically actuated micro-electro-mechanical-systems (MEMS). The discharge current transients (DCT), thermally stimulated depolarization current (TSDC) and Kelvin probe force microscopy (KPFM) assessment methods have been applied to either MIM capacitors or electrostatic capacitive MEMS switches or both. For the first time, the KPFM methodology has been used to create a link between the results obtained from the DCT and TSDC techniques applicable for MIM and the results from MEMS switches. The comparison shows that the application of KPFM method to MIM and MEMS leads to the same results on the electrical properties of the dielectric material. This provides a novel powerful tool for the assessment of dielectric charging for MEMS switches using MIM capacitors which have much simpler layer structure. On the other hand the TSDC method reveals a continuous distribution of relaxation time constants, which supports the dependence of relaxation time constant calculated for MEMS on the duration of the observation time window.