This work presents a promising microfabrication technique employing the silicon-on-nothing (SON) process to form a 2{m} thick continuous monocrystalline silicon membrane over a vacuum cavity of 1{m} in depth. Utilizing the SON process, high fill-factor piezoelectric micromachined ultrasonic transducer (pMUT) arrays on an 8-inch silicon wafer with cavity widths ranging from 170{m} down to 38{m} have been demonstrated. Devices are designed with 15% scandium-doped aluminum nitride as the piezoelectric layer of the pMUT for both air-coupled and water-coupled applications. The air-coupled pMUTs show a peak displacement frequency from 0.8 to 1.6 MHz with a Q-factor between 120 to 194. The water-coupled pMUT arrays show a transmit pressure measured by a needle hydrophone, in DI water at a distance of 20 mm, ranging between 0.4 to 6.9 kPa/V with peak frequency between 5 to 13.4 MHz and fractional bandwidth 56 to 36%, respectively. The piezoelectric-over-SON process proposed here has the potential to gain traction in low-cost and high-yield pMUT manufacturing.
Choong, D.S.W., Chen, D.S.-., Goh, D.J., Liu, J., Ghosh, S., Koh, Y., et al. (2021). Silicon-On-Nothing ScAlN pMUTs. In IEEE International Ultrasonics Symposium, IUS (pp.1-4). 345 E 47TH ST, NEW YORK, NY 10017 USA : IEEE Computer Society [10.1109/IUS52206.2021.9593461].
Silicon-On-Nothing ScAlN pMUTs
Savoia A. S.;
2021-01-01
Abstract
This work presents a promising microfabrication technique employing the silicon-on-nothing (SON) process to form a 2{m} thick continuous monocrystalline silicon membrane over a vacuum cavity of 1{m} in depth. Utilizing the SON process, high fill-factor piezoelectric micromachined ultrasonic transducer (pMUT) arrays on an 8-inch silicon wafer with cavity widths ranging from 170{m} down to 38{m} have been demonstrated. Devices are designed with 15% scandium-doped aluminum nitride as the piezoelectric layer of the pMUT for both air-coupled and water-coupled applications. The air-coupled pMUTs show a peak displacement frequency from 0.8 to 1.6 MHz with a Q-factor between 120 to 194. The water-coupled pMUT arrays show a transmit pressure measured by a needle hydrophone, in DI water at a distance of 20 mm, ranging between 0.4 to 6.9 kPa/V with peak frequency between 5 to 13.4 MHz and fractional bandwidth 56 to 36%, respectively. The piezoelectric-over-SON process proposed here has the potential to gain traction in low-cost and high-yield pMUT manufacturing.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
