New Manufacturing Method For Capacitive Ultrasonic Transducers With Monocrystalline Membrane

A new method to manufacture capacitive micromachined ultrasonic transducers (cMUT) combining a wafer bonding and a sacrificial layer processes is introduced. Devices with monocrystalline silicon membranes over a polysilicon electrode have been manufactured. From impedance measurements in air of a monocell test device biased under 140 V, a resonance at 8.0 MHz and an electromechanical coupling coefficient of 45% have been found. Underwater pulse-echo experiments of a cell array are presented.