RF MEMS capacitive switch with leaky nanodiamond dielectric film

RF MEMS capacitive switches using leaky nanodiamond as a dielectric film are studied and compared with those using Si3N4. Characteristics of dielectric charging and discharging are analyzed at temperature ranging from − 196 °C to 150 °C. Electrical resistivity of leaky nanodiamond is measured to be lower than that of Si3N4 by 3 to 6 orders of magnitude at room temperature. Trapped charges in leaky nanodiamond dielectric discharge much more quickly than those in Si3N4 while the power dissipation of nanodiamond based switches remains low. As a result, charge trapping induced shift in electrostatic actuation voltage is greatly reduced compared to that with Si3N4 and becomes non-detectable under the reported conditions. RF MEMS capacitive switches based on leaky nanodiamond dielectric are, therefore, more reliable than those with Si3N4.

Research Highlights
► Fabricated MEMS switches were examined by CV measurements while MIM capacitor structures were applied to measure transient charging and discharging currents.
► Leaky nanodiamond with tunable electrical resistivity was proven to be a superior dielectric material with faster escape of trapped charges than silicon nitride at temperatures ranging from − 196 °C to 150 °C.
► Nanodiamond dielectric films are effective in preventing undesirable shift of actuation voltage and stiction of electrodes in RF switches due to dielectric charge trapping.