Temperature Stability of Electrode/AlScN Multilayer Systems for pMUT Process Integration

Kristina Bespalova; Glenn Ross; Mervi Paulasto-Kröckel; T.S. Abhilash; Cyril Karuthedath; Stefan Mertin; Tuomas Pensala

doi:10.1109/IUS46767.2020.9251496

Temperature Stability of Electrode/AlScN Multilayer Systems for pMUT Process Integration

Kristina Bespalova
, Glenn Ross
, Mervi Paulasto-Kröckel
, T.S. Abhilash
, Cyril Karuthedath
, Stefan Mertin
, Tuomas Pensala

Aalto University

Research output: Chapter in Book/Report/Conference proceeding › Conference article in proceedings › Scientific › peer-review

3 Citations (Scopus)

Abstract

In this study, Al 0.8 Sc 0.2 N multilayer structures phase stability, interfacial quality, and piezoelectric response were tested before and after annealing in wide range of temperatures and times. The thicknesses and sequence of the layers in the structures are a replica of the design used for the fabrication of piezoelectric micromachined ultrasonic transducers (pMUTs). Al, AlSi (1%), Al/Mo, and Mo have been assessed to choose the most reliable top electrode (TE) material for the structures. The piezoresponse of the structure was estimated by measuring the deflection of piezocantilevers as a function of voltage applied over the film. Membrane deflection at resonance frequency for AlScN- and AlN-based pMUTs was simulated in COMSOL Multiphysics. It is found that the structure with Mo TE layer is stable after annealing at 800°C for 300 h and at 1000 °C for 100 h. None of the structures formed any phases at the interface between the electrode layer and AlScN. Membrane deflection for structures with AlScN as piezolayer is almost three times higher as compared to structures with AlN as piezolayer. Moreover, the pMUT membrane deflection increases after annealing of the structure.

Original language	English
Title of host publication	2020 IEEE International Ultrasonics Symposium (IUS)
Publisher	IEEE Institute of Electrical and Electronic Engineers
Number of pages	4
ISBN (Electronic)	978-1-7281-5448-0
ISBN (Print)	978-1-7281-5449-7
DOIs	https://doi.org/10.1109/IUS46767.2020.9251496
Publication status	Published - 7 Sept 2020
MoE publication type	A4 Article in a conference publication
Event	IEEE International Ultrasonics Symposium, IUS - Las Vegas, United States Duration: 7 Sept 2020 → 11 Sept 2020

Publication series

Series	IEEE International Ultrasonics Symposium (IUS)
ISSN	1948-5719

Conference

Conference	IEEE International Ultrasonics Symposium, IUS
Country/Territory	United States
City	Las Vegas
Period	7/09/20 → 11/09/20

Funding

This work is part of the POSITION-II project funded by the ECSEL Joint Undertaking under grant number Ecsel-783132-Position-II-2017-IA (www.position-2.eu). Ms. Bespalova appreciates the funding from Aalto ELEC Doctoral School.

Keywords

Aluminium Scandium Nitride
pMUT
thin-film deposition
annealing

Access to Document

10.1109/IUS46767.2020.9251496

Cite this

@inproceedings{3e7f4008adc84999aee062d3d90a8792,

title = "Temperature Stability of Electrode/AlScN Multilayer Systems for pMUT Process Integration",

abstract = "In this study, Al 0.8 Sc 0.2 N multilayer structures phase stability, interfacial quality, and piezoelectric response were tested before and after annealing in wide range of temperatures and times. The thicknesses and sequence of the layers in the structures are a replica of the design used for the fabrication of piezoelectric micromachined ultrasonic transducers (pMUTs). Al, AlSi (1\%), Al/Mo, and Mo have been assessed to choose the most reliable top electrode (TE) material for the structures. The piezoresponse of the structure was estimated by measuring the deflection of piezocantilevers as a function of voltage applied over the film. Membrane deflection at resonance frequency for AlScN- and AlN-based pMUTs was simulated in COMSOL Multiphysics. It is found that the structure with Mo TE layer is stable after annealing at 800°C for 300 h and at 1000 °C for 100 h. None of the structures formed any phases at the interface between the electrode layer and AlScN. Membrane deflection for structures with AlScN as piezolayer is almost three times higher as compared to structures with AlN as piezolayer. Moreover, the pMUT membrane deflection increases after annealing of the structure.",

keywords = "Aluminium Scandium Nitride, pMUT, thin-film deposition, annealing",

author = "Kristina Bespalova and Glenn Ross and Mervi Paulasto-Kr{\"o}ckel and T.S. Abhilash and Cyril Karuthedath and Stefan Mertin and Tuomas Pensala",

note = "Publisher Copyright: {\textcopyright} 2020 IEEE.; IEEE International Ultrasonics Symposium, IUS ; Conference date: 07-09-2020 Through 11-09-2020",

year = "2020",

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doi = "10.1109/IUS46767.2020.9251496",

language = "English",

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}

Bespalova, K, Ross, G, Paulasto-Kröckel, M, Abhilash, TS , Karuthedath, C, Mertin, S & Pensala, T 2020, Temperature Stability of Electrode/AlScN Multilayer Systems for pMUT Process Integration. in 2020 IEEE International Ultrasonics Symposium (IUS). IEEE Institute of Electrical and Electronic Engineers, IEEE International Ultrasonics Symposium (IUS), IEEE International Ultrasonics Symposium, IUS, Las Vegas, Nevada, United States, 7/09/20. https://doi.org/10.1109/IUS46767.2020.9251496

Temperature Stability of Electrode/AlScN Multilayer Systems for pMUT Process Integration. / Bespalova, Kristina; Ross, Glenn; Paulasto-Kröckel, Mervi et al.
2020 IEEE International Ultrasonics Symposium (IUS). IEEE Institute of Electrical and Electronic Engineers, 2020. (IEEE International Ultrasonics Symposium (IUS)).

Research output: Chapter in Book/Report/Conference proceeding › Conference article in proceedings › Scientific › peer-review

TY - GEN

T1 - Temperature Stability of Electrode/AlScN Multilayer Systems for pMUT Process Integration

AU - Bespalova, Kristina

AU - Ross, Glenn

AU - Paulasto-Kröckel, Mervi

AU - Abhilash, T.S.

AU - Karuthedath, Cyril

AU - Mertin, Stefan

AU - Pensala, Tuomas

PY - 2020/9/7

Y1 - 2020/9/7

N2 - In this study, Al 0.8 Sc 0.2 N multilayer structures phase stability, interfacial quality, and piezoelectric response were tested before and after annealing in wide range of temperatures and times. The thicknesses and sequence of the layers in the structures are a replica of the design used for the fabrication of piezoelectric micromachined ultrasonic transducers (pMUTs). Al, AlSi (1%), Al/Mo, and Mo have been assessed to choose the most reliable top electrode (TE) material for the structures. The piezoresponse of the structure was estimated by measuring the deflection of piezocantilevers as a function of voltage applied over the film. Membrane deflection at resonance frequency for AlScN- and AlN-based pMUTs was simulated in COMSOL Multiphysics. It is found that the structure with Mo TE layer is stable after annealing at 800°C for 300 h and at 1000 °C for 100 h. None of the structures formed any phases at the interface between the electrode layer and AlScN. Membrane deflection for structures with AlScN as piezolayer is almost three times higher as compared to structures with AlN as piezolayer. Moreover, the pMUT membrane deflection increases after annealing of the structure.

AB - In this study, Al 0.8 Sc 0.2 N multilayer structures phase stability, interfacial quality, and piezoelectric response were tested before and after annealing in wide range of temperatures and times. The thicknesses and sequence of the layers in the structures are a replica of the design used for the fabrication of piezoelectric micromachined ultrasonic transducers (pMUTs). Al, AlSi (1%), Al/Mo, and Mo have been assessed to choose the most reliable top electrode (TE) material for the structures. The piezoresponse of the structure was estimated by measuring the deflection of piezocantilevers as a function of voltage applied over the film. Membrane deflection at resonance frequency for AlScN- and AlN-based pMUTs was simulated in COMSOL Multiphysics. It is found that the structure with Mo TE layer is stable after annealing at 800°C for 300 h and at 1000 °C for 100 h. None of the structures formed any phases at the interface between the electrode layer and AlScN. Membrane deflection for structures with AlScN as piezolayer is almost three times higher as compared to structures with AlN as piezolayer. Moreover, the pMUT membrane deflection increases after annealing of the structure.

KW - Aluminium Scandium Nitride

KW - pMUT

KW - thin-film deposition

KW - annealing

UR - https://www.scopus.com/pages/publications/85097866413

U2 - 10.1109/IUS46767.2020.9251496

DO - 10.1109/IUS46767.2020.9251496

M3 - Conference article in proceedings

SN - 978-1-7281-5449-7

T3 - IEEE International Ultrasonics Symposium (IUS)

BT - 2020 IEEE International Ultrasonics Symposium (IUS)

PB - IEEE Institute of Electrical and Electronic Engineers

T2 - IEEE International Ultrasonics Symposium, IUS

Y2 - 7 September 2020 through 11 September 2020

ER -

Bespalova K, Ross G, Paulasto-Kröckel M, Abhilash TS , Karuthedath C, Mertin S et al. Temperature Stability of Electrode/AlScN Multilayer Systems for pMUT Process Integration. In 2020 IEEE International Ultrasonics Symposium (IUS). IEEE Institute of Electrical and Electronic Engineers. 2020. (IEEE International Ultrasonics Symposium (IUS)). doi: 10.1109/IUS46767.2020.9251496

Temperature Stability of Electrode/AlScN Multilayer Systems for pMUT Process Integration

Abstract

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Keywords

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