Experimental Investigation of Acoustic Substrate Losses in 1850-MHz Thin Film BAW Resonators

Tuomas Pensala, Robert Thalhammer, James Dekker, Jyrki Kaitila

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)

Abstract

After optimizing for electromechanical coupling coefficient K2, the main performance improvement in the thin film bulk acoustic wave resonators and filters can be achieved by improving the Q value, i.e., minimizing the losses. In Bragg-reflector-based solidly mounted resonator technology, a significant improvement of Q has been achieved by optimizing the reflector not only for longitudinal wave, the intended operation mode, but also for shear waves. We have investigated the remaining acoustic radiation losses to the substrate in so-optimized 1850-MHz AlN resonators by removing the substrate underneath the resonators and comparing the devices with and without substrate by electrical characterization before and after the substrate removal. Several methods to extract Q-values of the resonators are compared. Changes caused by substrate removal are observed in resonator behavior, but no significant improvement in Q-values can be confirmed. Loss mechanisms other than substrate leakage are concluded to dominate the resonator Q-value. Difficulties of detecting small changes in the Q-values of the resonators are also discussed.
Original languageEnglish
Pages (from-to)2544-2552
Number of pages9
JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Volume56
Issue number11
DOIs
Publication statusPublished - 2009
MoE publication typeA1 Journal article-refereed

Fingerprint

Resonators
Acoustics
resonators
Thin films
acoustics
Substrates
thin films
Bragg reflectors
Electromechanical coupling
Shear waves
longitudinal waves
coupling coefficients
sound waves
reflectors
S waves
leakage
Acoustic waves
filters
Radiation

Cite this

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title = "Experimental Investigation of Acoustic Substrate Losses in 1850-MHz Thin Film BAW Resonators",
abstract = "After optimizing for electromechanical coupling coefficient K2, the main performance improvement in the thin film bulk acoustic wave resonators and filters can be achieved by improving the Q value, i.e., minimizing the losses. In Bragg-reflector-based solidly mounted resonator technology, a significant improvement of Q has been achieved by optimizing the reflector not only for longitudinal wave, the intended operation mode, but also for shear waves. We have investigated the remaining acoustic radiation losses to the substrate in so-optimized 1850-MHz AlN resonators by removing the substrate underneath the resonators and comparing the devices with and without substrate by electrical characterization before and after the substrate removal. Several methods to extract Q-values of the resonators are compared. Changes caused by substrate removal are observed in resonator behavior, but no significant improvement in Q-values can be confirmed. Loss mechanisms other than substrate leakage are concluded to dominate the resonator Q-value. Difficulties of detecting small changes in the Q-values of the resonators are also discussed.",
author = "Tuomas Pensala and Robert Thalhammer and James Dekker and Jyrki Kaitila",
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Experimental Investigation of Acoustic Substrate Losses in 1850-MHz Thin Film BAW Resonators. / Pensala, Tuomas; Thalhammer, Robert; Dekker, James; Kaitila, Jyrki.

In: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 56, No. 11, 2009, p. 2544-2552.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Experimental Investigation of Acoustic Substrate Losses in 1850-MHz Thin Film BAW Resonators

AU - Pensala, Tuomas

AU - Thalhammer, Robert

AU - Dekker, James

AU - Kaitila, Jyrki

PY - 2009

Y1 - 2009

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AB - After optimizing for electromechanical coupling coefficient K2, the main performance improvement in the thin film bulk acoustic wave resonators and filters can be achieved by improving the Q value, i.e., minimizing the losses. In Bragg-reflector-based solidly mounted resonator technology, a significant improvement of Q has been achieved by optimizing the reflector not only for longitudinal wave, the intended operation mode, but also for shear waves. We have investigated the remaining acoustic radiation losses to the substrate in so-optimized 1850-MHz AlN resonators by removing the substrate underneath the resonators and comparing the devices with and without substrate by electrical characterization before and after the substrate removal. Several methods to extract Q-values of the resonators are compared. Changes caused by substrate removal are observed in resonator behavior, but no significant improvement in Q-values can be confirmed. Loss mechanisms other than substrate leakage are concluded to dominate the resonator Q-value. Difficulties of detecting small changes in the Q-values of the resonators are also discussed.

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JO - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

JF - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

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