Abstract: A fabrication method for microstructures with high aspect ratios is defined using via plugs and contact plugs. An etching channel is shaped as the microstructure is formed. Finally, an isotropic etching process is employed to remove the silicon substrate under the microstructure, thereby making a suspending microstructure with a high aspect ratio. In comparison with the prior art, the invention can save many photolithography steps and can be readily integrated into existing processes. Therefore, one can use the existing IC manufacturing equipment to make suspending microstructures with high aspect ratios.

Abstract: A microelectronic tunable capacitor and a method for fabricating the capacitor are described. The capacitor is formed by a micro-actuator, a first fixed capacitor plate and a second swayable capacitor plate suspended over the first plate. The micro-actuator is formed by a pair of fixed electrodes positioned spaced-apart from each other sandwiching without contact a suspended arm electrode swayable between the pair of fixed eletrodes. The second swayable capacitor plate is mounted to the suspended arm and sways by an electrostatic force between the pair of fixed electrodes to suitably adjust a desirable capacitance for the tunable capacitor.