Novel silicon nitride micromachined wide bandwidth ultrasonic transducers

Silicon micromachined ultrasonic devices have been fabricated using a CMOS-compatible process. Devices of up to 1 mm in size have been tested, with silicon nitride membranes of 1 /spl mu/m and 2 /spl mu/m thickness. The work has investigated the response of these ultrasonic receivers, as a function of membrane thickness and lateral dimensions. It is shown that the resultant surface micromachined transducers can operate over a wide bandwidth in air, without the resonant behaviour associated with previous devices.