a monolithically integrated , electromechanical microwave switch , capable of handling signals from dc to millimeter - wave frequencies , and an integrated electromechanical tunable capacitor are described . both electromechanical devices include movable beams actuated either by thermo - mechanical or by electrostatic forces . the devices are fabricated directly on finished silicon - based integrated circuit wafers , such as cmos , bicmos or bipolar wafers . the movable beams are formed by selectively removing the supporting silicon underneath the thin films available in a silicon - based integrated circuit technology , which incorporates at least one polysilicon layer and two metallization layers . a cavity and a thick , low - loss metallization are used to form an electrode above the movable beam . a thick mechanical support layer is formed on regions where the cavity is located , or substrate is bulk - micro - machined , i . e ., etched .