Figure-of-Merit Enhancement for Laterally Vibrating Lithium Niobate MEMS Resonators

Abstract

This paper reports on figure-of-merit (FoM) enhancement techniques for a new class of lithium niobate (LN)-based microelectromechanical systems laterally vibrating resonators (LVRs). A weighted electrode configuration is used to experimentally demonstrate a more than 2× enhancement for the device electromechanical coupling k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and an optimized reactive ion etch is used to attain straighter LN sidewalls and subsequently a 3× improvement in quality factor (Q=1300). As a result, the resonators orientated 30 ° to +y in the x-cut plane exhibited a k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of 21.7%, and a quality factor of 1300, effectively corresponding to an FoM of 280-the highest demonstrated to date for LVRs. These devices are expected to provide an unprecedented and unmatched platform for frequency-agile and adaptive RF filtering technology.