CMUT-in-CMOS ultrasonic transducer arrays with on-chip electronics

Integration of a 2D ultrasound transducer array with front-end signal conditioning electronics poses significant fabrication and packaging challenges due to the required number of elements and small element pitch. In this paper, we demonstrate a CMUT-in-CMOS approach that produces ultrasonic transducers and circuits on a single chip using a standard foundry CMOS process, augmented only with two blanket post-process steps for sacrificial etching and cavity sealing. 2D arrays as large as 16 times 16, with integrated on-chip buffers, switches and multiplexers were fabricated and successfully characterized. This approach provides a straightforward path to commercially viable 2D arrays for 3D medical imaging.