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
N1 - Funding Information:
ACKNOWLEDGMENT 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).
Funding Information:
Ms. Bespalova appreciates the funding from Aalto ELEC Doctoral School. M.Sc. Elmeri Österlund is acknowledged for his help with piezocantilever fabrication and XRD measurements.
Publisher Copyright:
© 2020 IEEE.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
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 - http://www.scopus.com/inward/record.url?scp=85097866413&partnerID=8YFLogxK
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
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 -