Hybrid microelectromechanical system tunable capacitor and associated fabrication methods

Abstract

A microelectromechanical system (MEMS) tunable capacitor having low loss and a corresponding high Q is provided. The tunable capacitor includes a first substrate having a first capacitor plate disposed thereon. A fixed pivot structure is disposed on the first surface of the first substrate, proximate the first capacitor plate. The fixed pivot structure as a point of attachment for a flexible membrane that extends outward from the fixed pivot and generally overlies the first capacitor plate. A second substrate is attached to the underside of the flexible membrane and a second capacitor plate is disposed thereon such that the first and second capacitor plates face one another in a spaced apart relationship. A MEMS actuator is operably in contact with the flexible membrane for the purpose of providing an actuation force to the flexible membrane, thereby varying the capacitance between the first and second capacitor plates. In one advantageous embodiment of the invention the first and second capacitor plates are formed of an HTS material and the first and second substrates may be formed of a low signal loss material that is compatible with the HTS materials. The MEMS actuator device used to provide actuation to the flexible membrane of the tunable capacitor may include a MEMS electrostatic flexible film actuator, a MEMS thermal arched beam actuator, a MEMS thermal bimorph actuator, a MEMS piezoelectric actuator or any other MEMS actuation device. Additionally, a method for making a tunable capacitor is provided.