Frequency Scaling Millimeter Wave Acoustic Resonators using Ion Beam Trimmed Lithium Niobate
Vakhtang Chulukhadze, Kenny Huynh, Jack Kramer, Michael E. Liao, Sinwoo Cho, Lezli Matto, Omar A. Barrera, Can Cui, Mark S. Goorsky, Ruochen Lu
Abstract
SummaryThis paper reports a method of frequency scaling millimeter wave thin-film lithium niobate (LiNbO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> ) acoustic resonators using ion beam assisted Argon gas cluster trimming whilst maintaining a high figure of merit (FoM) and averting ultra-thin-film fabrication difficulties. A transferred 100 nm thick 128° Y-cut LiNbO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> thin film is trimmed to a thickness of 75 nm. Consequently, a 24.4 GHz first-order antisymmetric mode (A1) resonator with a high k <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of 34.3%, a Q of 54, and an FoM of 18.5 is presented. The quality of the film was maintained during the trimming process, proven by material-level analysis, and exhibited a similar f•Q product compared with resonators fabricated using the original film. These results show a viable and less complex path toward further frequency scaling acoustic devices.