Properties of contactless and contacted charging in MEMS capacitive switches

• The properties of contacted and contact-less charging have been investigated and correlated.
• Contact-less charging can produce partial compensation and mitigates the overall charging.
• The characteristic time of charging process is much smaller for the case of contacted charging.
• The magnitude of charging current is much larger for the case of contacted charging.
• The equivalent charge density for the two charging processes is similar in magnitude.

The dielectric charging in MEMS capacitive switches is a complex effect. The high electric field during pull-down causes intrinsic free charge migration and dipole orientation as well as charge injection. The macroscopic dipole moment of the first two mechanisms is opposite to the one arising from charge injection. This causes partial compensation hence mitigates the overall charging and increases the device lifetime. The charging due to intrinsic free charge migration and dipole orientation can be monitored under contactless electric field application in the pull-up state. The paper investigates the characteristics of contactless charging and compares them with the ones of contacted charging. The characteristics of the discharging process that follows each charging procedure are also presented.