A Film Bulk Acoustic Resonator Based on Ferroelectric Aluminum Scandium Nitride Films

Jialin Wang; Mingyo Park; Stefan Mertin; Tuomas Pensala; Farrokh Ayazi; Azadeh Ansari

doi:10.1109/JMEMS.2020.3014584

A Film Bulk Acoustic Resonator Based on Ferroelectric Aluminum Scandium Nitride Films

Jialin Wang^*
, Mingyo Park
, Stefan Mertin
, Tuomas Pensala
, Farrokh Ayazi
, Azadeh Ansari

^*Corresponding author for this work

Georgia Institute of Technology

Research output: Contribution to journal › Article › Scientific › peer-review

144 Citations (Scopus)

Abstract

This work reports on the first demonstration of the frequency tuning and intrinsic polarization switching of film bulk acoustic resonators (FBARs), based on sputtered AlScN piezoelectric thin films with Sc/(Al + Sc) ratio of approx. 30%. A box-like ferroelectric hysteresis behavior of 900 nm-thick Al0.7Sc0.3N sputtered films is obtained, showing a coercive electric field at 3 MV/cm. The fundamental thickness-mode resonance of the bulk acoustic wave (BAW) resonator is measured at 3.17 GHz frequency with an excellent electromechanical coupling coefficient (kt 2) of 18.1%. The FBAR frequency response is studied, in both (i) the linear tuning regime, upon application of DC electric fields below the coercive field; as well as (ii) the polarization switching regime, upon application of electric fields above the coercive field. A large linear tuning range of 215 ppm × μ m /V is obtained in case (i), resulting from the high scandium content. The series resonance frequency of the FBARs is switched ON and OFF in (ii) upon application of 350 V unipolar waveform across the Al0.7Sc0.3N thickness. This is the first demonstration of the intrinsically switchable AlN-based FBARs with a large tuning range; and record high k t2 reported for AlN-based FBARs to date. Furthermore, this work paves the way for realization of tunable and switchable wideband acoustic filters operating at super high frequency ranges (SHF). [2020-0203].

Original language	English
Article number	9169713
Pages (from-to)	741-747
Number of pages	7
Journal	Journal of Microelectromechanical Systems
Volume	29
Issue number	5
DOIs	https://doi.org/10.1109/JMEMS.2020.3014584
Publication status	Published - Oct 2020
MoE publication type	A1 Journal article-refereed

Funding

Manuscript received May 15, 2020; revised July 28, 2020; accepted August 1, 2020. Date of publication August 17, 2020; date of current version October 7, 2020. This work was supported in part by the National Science Foundation under Grant ECCS-1542174 and in part by the National Science Foundation CAREER Award under Grant ECCS-1944304. Subject Editor M. Rais-Zadeh. (Corresponding author: Jialin Wang.) Jialin Wang, Mingyo Park, Farrokh Ayazi, and Azadeh Ansari are with the School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA (e-mail: [email protected]; [email protected]; [email protected]; [email protected]).

Keywords

acoustic resonators
aluminum scandium nitride
fbar
Ferroelectric
filters
frequency tuning
piezoelectric films

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10.1109/JMEMS.2020.3014584

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title = "A Film Bulk Acoustic Resonator Based on Ferroelectric Aluminum Scandium Nitride Films",

abstract = "This work reports on the first demonstration of the frequency tuning and intrinsic polarization switching of film bulk acoustic resonators (FBARs), based on sputtered AlScN piezoelectric thin films with Sc/(Al + Sc) ratio of approx. 30\%. A box-like ferroelectric hysteresis behavior of 900 nm-thick Al0.7Sc0.3N sputtered films is obtained, showing a coercive electric field at 3 MV/cm. The fundamental thickness-mode resonance of the bulk acoustic wave (BAW) resonator is measured at 3.17 GHz frequency with an excellent electromechanical coupling coefficient (kt 2) of 18.1\%. The FBAR frequency response is studied, in both (i) the linear tuning regime, upon application of DC electric fields below the coercive field; as well as (ii) the polarization switching regime, upon application of electric fields above the coercive field. A large linear tuning range of 215 ppm × μ m /V is obtained in case (i), resulting from the high scandium content. The series resonance frequency of the FBARs is switched ON and OFF in (ii) upon application of 350 V unipolar waveform across the Al0.7Sc0.3N thickness. This is the first demonstration of the intrinsically switchable AlN-based FBARs with a large tuning range; and record high k t2 reported for AlN-based FBARs to date. Furthermore, this work paves the way for realization of tunable and switchable wideband acoustic filters operating at super high frequency ranges (SHF). [2020-0203].",

keywords = "acoustic resonators, aluminum scandium nitride, fbar, Ferroelectric, filters, frequency tuning, piezoelectric films",

author = "Jialin Wang and Mingyo Park and Stefan Mertin and Tuomas Pensala and Farrokh Ayazi and Azadeh Ansari",

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AU - Park, Mingyo

AU - Mertin, Stefan

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AU - Ayazi, Farrokh

AU - Ansari, Azadeh

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N2 - This work reports on the first demonstration of the frequency tuning and intrinsic polarization switching of film bulk acoustic resonators (FBARs), based on sputtered AlScN piezoelectric thin films with Sc/(Al + Sc) ratio of approx. 30%. A box-like ferroelectric hysteresis behavior of 900 nm-thick Al0.7Sc0.3N sputtered films is obtained, showing a coercive electric field at 3 MV/cm. The fundamental thickness-mode resonance of the bulk acoustic wave (BAW) resonator is measured at 3.17 GHz frequency with an excellent electromechanical coupling coefficient (kt 2) of 18.1%. The FBAR frequency response is studied, in both (i) the linear tuning regime, upon application of DC electric fields below the coercive field; as well as (ii) the polarization switching regime, upon application of electric fields above the coercive field. A large linear tuning range of 215 ppm × μ m /V is obtained in case (i), resulting from the high scandium content. The series resonance frequency of the FBARs is switched ON and OFF in (ii) upon application of 350 V unipolar waveform across the Al0.7Sc0.3N thickness. This is the first demonstration of the intrinsically switchable AlN-based FBARs with a large tuning range; and record high k t2 reported for AlN-based FBARs to date. Furthermore, this work paves the way for realization of tunable and switchable wideband acoustic filters operating at super high frequency ranges (SHF). [2020-0203].

AB - This work reports on the first demonstration of the frequency tuning and intrinsic polarization switching of film bulk acoustic resonators (FBARs), based on sputtered AlScN piezoelectric thin films with Sc/(Al + Sc) ratio of approx. 30%. A box-like ferroelectric hysteresis behavior of 900 nm-thick Al0.7Sc0.3N sputtered films is obtained, showing a coercive electric field at 3 MV/cm. The fundamental thickness-mode resonance of the bulk acoustic wave (BAW) resonator is measured at 3.17 GHz frequency with an excellent electromechanical coupling coefficient (kt 2) of 18.1%. The FBAR frequency response is studied, in both (i) the linear tuning regime, upon application of DC electric fields below the coercive field; as well as (ii) the polarization switching regime, upon application of electric fields above the coercive field. A large linear tuning range of 215 ppm × μ m /V is obtained in case (i), resulting from the high scandium content. The series resonance frequency of the FBARs is switched ON and OFF in (ii) upon application of 350 V unipolar waveform across the Al0.7Sc0.3N thickness. This is the first demonstration of the intrinsically switchable AlN-based FBARs with a large tuning range; and record high k t2 reported for AlN-based FBARs to date. Furthermore, this work paves the way for realization of tunable and switchable wideband acoustic filters operating at super high frequency ranges (SHF). [2020-0203].

KW - acoustic resonators

KW - aluminum scandium nitride

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ER -

A Film Bulk Acoustic Resonator Based on Ferroelectric Aluminum Scandium Nitride Films

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