[17p-B3-1~18] 6.1 Ferroelectric thin films

2:00 PM - 2:15 PM JST(5:00 AM - 5:15 AM UTC)Presentation by Applicant for JSAP Young Scientists Presentation Award

[17p-B3-5] Intrinsic electromechanical coupling coefficient k₃₃² evaluation method
from HBAR using the difference between dielectric constant ε^Tand ε^S

〇(M2)Hiroki Uchida^1,2, Kohei Ekida^1,2, Yohkoh Shimano^1,2, Takahiko Yanagitani^1,2 (1.Waseda Univ., 2.ZAIKEN)

Keywords:

electromechanical coupling coefficient,BAW filter,dielectric constant

The electromechanical coupling coefficient k_t² is one of the important parameters that determine the performance of piezoelectric devices. The resonance-antiresonance method is often used for k_t² evaluation, but this method requires substrate removal, such as FBAR. On the other hand, various k_t² evaluation methods have been reported that do not require substrate removal, e.g., the conversion loss method, resonant frequency ratio method, and so on.
In this study, we propose a new method for extracting the intrinsic k_t² from HBAR without substrate removal using the difference between low frequency and high frequency dielectric constant of e^T and e^S. In the frequency lower than acoustic resonant frequency, the dielectric constant is e^T, while in the higher than acoustic resonant frequency, the dielectric constant is e^S (<e^T). Since the difference between e^T and e^S is caused by the electromechanical coupling, we can estimate intrinsic k_t² from these values.