9.5 % Scandium Doped ALN PMUT Compatible with Pre-Processed CMOS Substrates
Eyglis Ledesma, Iván Zamora, A. Uranga, N. Barniol
Abstract
This paper presents an 80 μm squared piezoelectric micromachined ultrasonic transducer (PMUT) using 9.5 % scandium-doped aluminum nitride (AlScN). The improvement in the effective piezoelectric coefficient (e <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31,f</sub> ) and consequently in the membrane displacement was demonstrating according with the FEM simulation. The proposed device has a high piezoelectric coefficient factor (k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) in air, 2.76 %, and also in liquid environment, 1.12 %. The output pressure normalized at 1.5 mm in Fluorinert gives 12.57 kPa/V/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , ~ 9 times higher than 7x7 AlScN array (1.4 kPa/V/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ). Pulse-echo experiment was validated with a single PMUT considering as reflected surface the air-liquid interface.