Micromachined ultrasound transducers with improved coupling factors from a CMOS compatible process

Abstract

How the BiCMOS process was modified to meet the demands for ultrasound generation and reception is presented. Bias and driving voltages was reduced down to the 10 V range. The electromechanical coupling is almost comparable with that for piezoelectric transducers. The measurements exhibit sound pressures and bandwidths that are at least comparable with those of conventional piezoelectric transducer arrays.