Monolithic Integration of P(VDF-TrFE) Thin Film on CMOS for Wide-band Ultrasonic Transducer Arrays

We developed a novel ultrasonic transducer with a P(VDF-TrFE) thin film monolithically integrated on a CMOS LSI. Its higher sensitivity and wider bandwidth in the 20 MHz range compared to a conventional PZT transducer is demonstrated. The P(VDF-TrFE) is an attractive piezoelectric sensor material with an excellent piezoelectric constant and low acoustic impedance matched to human tissue. However, it is difficult to miniaturize the device like a 2D array, and due to its low dielectric constant, the transducer is susceptible to parasitic capacitance of the connection circuity. This problem is solved by the monolithic formation of P(VDF-TrFE) transducers on CMOS LSI. In this study, such an ultrasonic array (16 elements × 4 channels) with a single-element area (190 × 190 μm
²
) was fabricated, and the receiving acoustic characteristics were evaluated.