Capacitive micromachined ultrasonic transducer (cMUT) array for the frequency range below 500 kHz

A new capacitive micromachined ultrasonic transducer (cMUT) array for the frequency range up to 500 kHz has been fabricated and successfully tested. The new setup of the ultrasonic transducer array, the process flow, the simulation as well as a new concept for a further transducer type are major topics of this paper. The presented ultrasonic transducer has been fabricated on 4" [100] silicon wafers with conductive polycrystalline silicon as diaphragm and a perforated nickel structure as backplate. The perforated nickel backplate with a thickness between 10-20 /spl mu/m has been realized by an electroplating process. The transducer array consists of groups of membranes. Each group realized by single anisotropic backside openings.