Phased Array Based on AlScN Piezoelectric Micromachined Ultrasound Transducers Monolithically Integrated on CMOS

• Published in: IEEE electron device letters Vol. 43; no. 7; pp. 1113 - 1116
• Main Authors: Zamora, I., Ledesma, E., Uranga, A., Barniol, N.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic beams; Acoustic transducers; Acoustics; Analog circuits; Beam steering; CMOS; Delays; Directivity; Imaging; Micromachining; Phased arrays; piezoelectric micromachined ultrasonic transducers (PMUT); Piezoelectricity; PMUT-on-CMOS; Signal to noise ratio; Transducers; Ultrasonic imaging; ultrasound imaging
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2022.3175323

In this work we present an array of piezoelectric micromachined ultrasound transducer (PMUT's) based on AlScN piezoelectric layer, monolithically integrated on top of a 130 nm CMOS circuit. The <inline-formula> <tex-math notation="LaTeX">{7}\times {7} </tex-math></inline-formula> array along with the analog-front-end circuit has been configured to work as a linear phased array. Experiments carried out have demonstrated the homogeneous PMUT's behavior, showing a small dispersion in terms of frequency, bandwidth, and sensitivity. The feasibility of easily performing a transmission beam steering and focusing has been proven. In particular, the beam directivity has been characterized in terms of the width of the main lobe. The integrated CMOS analog-front-end allows the reduction of parasitic elements and noise, improving the signal to noise ratio (SNR). As a proof of concept, a B-mode image, with a 16 dB dynamic range, using a single <inline-formula> <tex-math notation="LaTeX">{7}\times {1} </tex-math></inline-formula> AlScN PMUT-on-CMOS channel as a receiver has been obtained.