Anchor Loss Reduction for Square-Extensional Mode MEMS Resonator Using Tethers With Auxiliary Structures

Abstract

In this article, a new approach by introducing auxiliary structures in the tethers of a microelectromechanical system (MEMS) resonator is presented to reduce anchor loss. A capacitive square-extensional (SE) mode resonator with folded beam tether is adopted to verify the feasibility of the proposed approach in both finite-element method (FEM) analysis and measurement. In FEM simulations, a perfectly matched layer (PML) boundary condition is applied to estimate anchor loss of the designed MEMS resonators. With the aid of the auxiliary structures, quality factors ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}\text{s}$ </tex-math></inline-formula> ) of the designed SE mode MEMS resonators are significantly improved. The measured <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> of the fabricated SE mode resonator is improved by approximately 62% after introducing auxiliary structures in the tethers of the resonator without any further treatments on the resonator structure or tether design. The proposed approach provides a simple and effective way to suppress anchor loss and hence improve <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> for the presented MEMS resonators.