A new class of capacitive micromachined ultrasonic transducers

A new set-up of capacitive micromachined ultrasonic transducers (cMUT) will be described that recently have been successfully realized. This new transducer design utilizes a structured silicon oxide sacrificial layer as well as a highly doped and, therefore, conductive membrane of polycrystalline silicon. So far, cMUT have been produced with resonance frequencies in the range from 1 to 4 MHz. These devices have been applied to a displacement measurement in air.