Review of Device and Reliability Physics of Dielectrics in Electrostatically Driven MEMS Devices

Dielectric Charge Control in Electrostatic MEMS Positioners/Varactors

“…However the commercial use of these devices is hindered by reliability problems limiting their lifetime [1]. Typical structures of capacitive MEMS devices include silicon oxide and nitride as the most common dielectric materials (see the recent review [2] and references cited there). For those capacitive MEMS, the charge accumulated in dielectric layers has a significant impact on the behaviour of such devices by altering the electric field distribution in the gap and causing offset shifts in the capacitance-voltage (C-V ) characteristic, as is shown, for instance, in [3]- [6].…”

Characterization and reliability studies towards piezoelectrically actuated RF-MEMS switches

“…Stiction is caused by an enhanced adhesion force between the two contact surfaces. The adhesion force is a tensile force needed to be overcome to separate the two contact surfaces, including capillary force, van der Waals forces and electrostatic force between the surfaces [34]. Stiction will happen, when the adhesion force is larger than the spring force even when the actuation voltage is removed.…”

“…The magnitude of adhesion force strongly depends on the real contact area [34]. The two main contributions of adhesion force are capillary force and Van der Waals force.…”

“…Water molecules are usually present at any surfaces because of spontaneous fluid condensation [34,36]. The formation of small liquid bridges between two hydrophilic surfaces is called capillary condensation.…”

“…The force of hydrogen bonding is weaker than the covalent bonding force but is much stronger than the van der Waals force. Therefore, the capillary force originating from the dipole attraction between water molecules significantly increases the adhesion force [34].…”