10 Investigation of Charge Accumulation in Si_3N_4/SiO_2 Dielectric Stacks for Electrostatically Actuated NEMS/MEMS Reliability

摘要

Dielectric charging, understood to mean the accumulation of electric charge in the dielectric, constitutes a major failure mechanism that inhibits the commercialization of various electrostatically actuated micro- and nanoelectromechanical systems (MEMS and NEMS) [1]. In such NEMS/ MEMS devices containing dielectric materials, dielectric charging always occurs when there is a strong electric field. Stiction induced by dielectric charging is considered the main failure mechanism in electrostatic NEMS/MEMS devices especially for electrostatic capacitive MEMS switches. The accumulated charge in the dielectric of a capacitive MEMS switch will cause the metal bridge to be partially or fully pulled down, degrading the on–off ratio of the switch [2–5]. Charge accumulation in the dielectric must be avoided for high reliability in such devices. Though the topic has been intensively investigated, little information is available in the literature providing a fundamental solution to this problem; even the charging processes are still not thoroughly understood. Therefore, thoroughly understanding the charge accumulation mechanisms to develop a strategy to control dielectric charging is still crucial for minimizing charge accumulation in the dielectric.