Poly-SiGe-based CMUT array with high acoustical pressure

Abstract

Capacitive micromachined ultrasound transducers (CMUT) have the potential to enable 3-D ultrasound imaging. This paper reports a novel manufacturable buildup of a CMUT device which is CMOS compatible. The approach allows high density integration and independent optimization of the CMUT device and the integrated electronics. The CMUT device makes use of polycrystalline silicon-germanium (poly-SiGe) as the structural material, in combination with silicon carbide (SiC) as the dielectric layer to allow high electrical field in the transduction gap. Breakdown voltage of above 500V is demonstrated. Transmit pressure normalized to the surface of the transducer is as high as 580kPa for DC and AC voltages of 340 and 75V, respectively. Initial characterization of pulse-echo measurement is also reported.