US Patent 7612483 Harmonic cMUT devices and fabrication methods

Harmonic capacitive micromachined ultrasonic transducer (“cMUT”) devices and fabrication methods are provided. In a preferred embodiment, a harmonic cMUT device generally comprises a membrane having a non-uniform mass distribution. A mass load positioned along the membrane can be utilized to alter the mass distribution of the membrane. The mass load can be a part of the membrane and formed of the same material or a different material as the membrane. The mass load can be positioned to correspond with a vibration mode of the membrane, and also to adjust or shift a vibration mode of the membrane. The mass load can also be positioned at predetermined locations along the membrane to control the harmonic vibrations of the membrane. A cMUT can also comprise a cavity defined by the membrane, a first electrode proximate the membrane, and a second electrode proximate a substrate. Other embodiments are also claimed and described.