[17p-D505-1~11] 1.6 Ultrasonics

△ [17p-D505-6] Comparison of experimental result and FEM simulation for electrode area dependence in k_t² evaluation of piezoelectric films in film/substrate structure

〇(M2)Ryo Seki^1,2, Yuki Shimizu^1,2, Takahiko Yanagitani^1,2,3,4,5 (1.Waseda Univ., 2.ZAIKEN, 3.JST-CREST, 4.JST-FOREST, 5.JST-START)

Keywords:piezoelectric film, HBAR, electromechanical coupling coefficient

Electromechanical coupling coefficient k_t² is an important factor for evaluating the performance of BAW devices. The resonance-antiresonance method, which is standard for k_t² evaluation, needs self-standing film structure (FBAR). On the other hand, we previously proposed various k_t² extraction methods without removing the substrate such as resonant frequency ratio method, conversion loss (CL) method with electromagnetic signal and CL method with subtracting acoustic losses. In this study, we analyzed the electrode area dependence of k_t², which was confirmed by actual measurements, using the finite element method (FEM) and compared the results.