Enhancing AIN PMUTs' acoustic responsivity within a MEMS-on-CMOS process
Ledesma, Eyglis (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Zamora, Iván (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Uranga del Monte, Aránzazu (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Torres, Francesc 1948- (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Barniol i Beumala, Núria (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)

Date:	2021
Abstract:	In this paper, guidelines for the optimization of piezoelectrical micromachined ultrasound transducers (PMUTs) monolithically integrated over a CMOS technology are developed. Higher acoustic pressure is produced by PMUTs with a thin layer of AlN piezoelectrical material and SiN as a passive layer, as is studied here with finite element modeling (FEM) simulations and experimental characterization. Due to the thin layers used, parameters such as residual stress become relevant as they produce a buckled structure. It has been reported that the buckling of the membrane due to residual stress, in general, reduces the coupling factor and consequently degrades the efficiency of the acoustic pressure production. In this paper, we show that this buckling can be beneficial and that the fabricated PMUTs exhibit enhanced performance depending on the placement of the electrodes. This behavior was demonstrated experimentally and through FEM. The acoustic characterization of the fabricated PMUTs shows the enhancement of the PMUT performance as a transmitter (with 5 kPa V surface pressure for a single PMUT) and as a receiver (12. 5 V MPa) in comparison with previously reported devices using the same MEMS-on-CMOS technology as well as state-of-the-art devices.
Grants:	Agencia Estatal de Investigación PID2019-108270RB-I00
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	PMUT ; Ultrasound ; CMOS ; MEMS-on-CMOS ; Acoustic responsivity ; AIN ; Piezoelectric transducers ; PMUT-on-CMOS
Published in:	Sensors (Basel, Switzerland), Vol. 21, Issue 24 (December 2021) , art. 8447, ISSN 1424-8220

DOI: 10.3390/s21248447
PMID: 34960541

12 p, 5.0 MB

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