Large Scale High Voltage 192+192 Row-Column Addressed CMUTs Made with Anodic Bonding

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This work presents the fabrication process of anodically bonded 192+192 2D row-column addressed (RCA) capacitive micromachined ultrasonic transducer (CMUT) arrays. Four large 2.1 by 2.1 cm2 arrays with a resonance frequency of 7.5 MHz in water and ⋋/2 element pitch at 95 µm are shown successfully fabricated. The arrays exhibit a 100% bond yield by anodically bonding an SOI wafer to a borosilicate glass wafer structured with CMUT cavities. A silicon nitride layer has been used at the wafer bonding interface to insulate the top and bottom electrodes for high voltage operation to at least ±200V DC bias. Electrical measurements have been performed on 192+192 RCA arrays and smaller 16+16 RCA arrays. These showed a resonance frequency of approximately 18 MHz in air at a bias of -200 V, corresponding to 80% of the pull-in voltage and 50 mV AC, with a coupling coefficient of 26.8 %.
Original languageEnglish
Title of host publication2020 IEEE International Ultrasonics Symposium (IUS)
Number of pages4
Publication date2020
ISBN (Print)978-1-7281-5449-7
ISBN (Electronic)978-1-7281-5448-0
Publication statusPublished - 2020
Event2020 IEEE International Ultrasonics Symposium - Virtual symposium, Las Vegas, United States
Duration: 6 Sep 202011 Sep 2020


Conference2020 IEEE International Ultrasonics Symposium
LocationVirtual symposium
CountryUnited States
CityLas Vegas
Internet address

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